Legion Of The Bouncy Castle Inc

CVE	Summary	Severity	CVSS	EPSS	Priority
CVE-2026-8763	Certificate name-constraint bypass in Bouncy Castle for Java allows a crafted certificate to escape X.509 permitted/excluded subtree restrictions by appending a trailing dot to an rfc822Name (email) or URI host, or by prepending RDNs ahead of a permitted directoryName. Any relying party using BC's PKIXNameConstraintValidator (via CertPathValidator/CertPathBuilder) to enforce name constraints can be tricked into trusting an identity a constrained CA was never authorized to issue, enabling impersonation and effective authentication bypass. There is no public exploit identified at time of analysis, but the vendor rates it 9.3 (Critical) and a fix is available.	CRITICAL	9.3	0.3%	47
CVE-2026-59638	TLS hostname-verification bypass in the Bouncy Castle for Java JSSE provider (BCJSSE) ships the legacy certificate-CN fallback enabled by default, even though the vendor documentation states it is opt-in and gated behind the org.bouncycastle.jsse.client.checkCnFallback property. Affected are BC-Java before 1.85, BC-LTS before 2.73.12, and BC-FJA (FIPS) TLS module bctls-fips before 1.0.24, 2.0.24 and 2.1.24; a MITM-positioned attacker can present a SAN-less certificate whose Subject CN names the victim host and have it silently accepted, defeating name-constraint protections and enabling interception of TLS traffic (CWE-297). This carries a CVSS 4.0 base of 9.3, but there is no public exploit identified at time of analysis and it is not in CISA KEV.	CRITICAL	9.3	0.3%	47
CVE-2026-59650	Private key recovery in Bouncy Castle for Java (bc-java before 1.85, bc-lts-java before 2.73.12) affects the DH agreement code path, where a peer-supplied public value is exponentiated with the local private key without full range/subgroup validation. A malicious protocol peer can submit small-order or out-of-range Diffie-Hellman elements to mount a small-subgroup confinement attack and, when the local private key is static/reused, gradually recover it via CRT - enabling decryption and impersonation. No public exploit identified at time of analysis; the fix is a vendor-released patch and the vulnerability is not listed in CISA KEV.	CRITICAL	9.3	0.3%	47
CVE-2026-58062	Certificate revocation-check bypass in the Bouncy Castle for Java (bc-java) PKIX provider allows a validly-signed OCSP response issued for one certificate to be accepted as proof-of-status for a different certificate, because the stapled response is not bound to the CertID of the certificate actually being checked. This means a revoked end-entity certificate can pass PKIXRevocationChecker validation when a 'good' OCSP response for another serial (e.g. the CA's) is supplied, defeating revocation enforcement in TLS/PKI clients that rely on OCSP stapling. Affected releases are bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FJA (FIPS) before 2.0.2 and 2.1.3; no public exploit identified at time of analysis and it is not listed in CISA KEV.	CRITICAL	9.3	0.2%	47
CVE-2025-14813	GOST CTR block cipher in Bouncy Castle BC-JAVA processes only the first 255 blocks correctly, causing silent data corruption in encryption/decryption operations for longer messages. Affects BC-JAVA versions 1.59 through 1.83, with fix available in version 1.84. Local attack vector (CVSS AV:L) with critical CVSS 9.4 score reflects potential for both confidentiality and integrity compromise when applications process GOST-encrypted data streams exceeding 255 blocks (~4KB). No KEV listing or public	CRITICAL	9.3	0.0%	47
CVE-2026-5598	Non-constant time comparison operations in the Legion of the Bouncy Castle BC-JAVA cryptographic library (core modules, versions 2.17.3 through 1.83) expose FrodoKEM private keys to timing side-channel attacks, enabling remote unauthenticated attackers to extract cryptographic secrets through statistical analysis of operation timing variations. CVSS 4.0 score of 10.0 reflects maximum confidentiality and integrity impact across system and subsequent contexts. EPSS probability is low (0.04%, 14th percentile) and no active exploitation is confirmed, but SSVC framework rates this as automatable with total technical impact. Vendor patch available in BC-JAVA 1.84.	HIGH	8.9	0.0%	45
CVE-2026-58060	Uncontrolled memory allocation in Bouncy Castle for Java's HSS public-key parser allows remote unauthenticated attackers to exhaust JVM heap memory by supplying a crafted public key with an arbitrarily large HSS level count (L value), causing denial of service during signature verification. All three product lines are affected: bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FIPS (bc-fja) before 2.0.2/2.1.3 depending on series. No public exploit has been identified at time of analysis and no CISA KEV listing exists, but the AV:N/AC:L/PR:N attack profile and Bouncy Castle's ubiquity as a Java crypto dependency make this a credible availability risk for any service accepting external HSS/LMS key material.	HIGH	8.7	0.4%	44
CVE-2026-58059	CPU exhaustion in Bouncy Castle for Java allows remote attackers to cause denial of service by supplying X.500 distinguished name attribute values densely packed with RFC 4514 special characters or leading/trailing spaces. The root cause is a quadratic-time O(n²) escaping algorithm in `IETFUtils.valueToString()` that inserts backslashes into the buffer being actively scanned - triggerable through `X500Name.toString()`, `.equals()`, or `.hashCode()`, methods commonly invoked during TLS certificate and LDAP DN processing. No public exploit has been identified beyond the vendor's own regression test, and this vulnerability is not listed in CISA KEV, though the CVSS 4.0 score of 8.7 with AV:N/PR:N signals meaningful exposure for Internet-facing Java services.	HIGH	8.7	0.3%	44
CVE-2026-8798	Unbounded retry loops in BC-FJA's JNI native entropy layer cause calling threads to hang indefinitely when Intel RDSEED or RDRAND instructions persistently fail, producing a non-interruptible thread-level denial of service in any Java FIPS application backed by bc-fips 2.1.x before 2.1.3. The affected JNI seeding routine re-issues the CPU entropy instruction without any iteration limit whenever the carry flag signals failure - a condition reproducible by hardware entropy source faults, DRBG exhaustion under heavy multi-core contention, or hypervisors that do not forward these Intel instructions to guest VMs. No public exploit code has been identified and the vulnerability is not listed in CISA KEV, but the conditions are routinely present in virtualized environments where hypervisors commonly withhold RDRAND/RDSEED forwarding, making this a realistic operational risk for enterprise Java FIPS deployments in cloud or VM-based infrastructure.	HIGH	8.7	0.3%	44
CVE-2026-59646	Memory exhaustion denial-of-service in Bouncy Castle's DTLS implementation allows remote unauthenticated attackers to crash or degrade Java applications by sending crafted handshake messages with inflated 24-bit length fields. Affected are bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FJA (bctls-fips) before 1.0.24, 2.0.24, or 2.1.24 depending on the deployed branch. The buffer allocation occurs pre-authentication during the DTLS handshake reassembly phase - before any signature or Finished verification - making this exploitable without credentials against any exposed DTLS endpoint. No public exploit code has been identified and the vulnerability is not listed in CISA KEV.	HIGH	8.7	0.3%	44
CVE-2026-59640	Bouncy Castle for Java's OpenPGP session-key decryption path re-exposes the Mister-Zuccherato adaptive-chosen-ciphertext oracle by failing to suppress the legacy CFB 'quick check' on the PKESK/session-key route, enabling an attacker with decryption oracle access to recover plaintext from SEIPD v1 encrypted messages. Affected are bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FJA (bcpg-fips) across the 1.0.X, 2.0.X, and 2.1.X series - three distinct product lines used broadly in enterprise and open-source Java applications. No public exploit or CISA KEV listing has been identified at time of analysis; however, the attack technique is well-established in cryptographic literature dating to the Mister-Zuccherato paper.	HIGH	8.7	0.3%	44
CVE-2026-59644	CPU exhaustion in Bouncy Castle for Java's MLS (Messaging Layer Security) implementation allows a network attacker to trigger unbounded HKDF key-derivation iterations by supplying a crafted 32-bit generation counter in an MLS message. The hash-ratchet in GroupKeySet.get(int generation) advances one HKDF step per skipped generation without any upper bound, so a maximally crafted counter forces up to ~4.29 billion derivation steps on the receiving process. Scored CVSS 4.0 at 8.7 with High availability impact and no authentication prerequisites per vendor scoring; no public exploit code or KEV listing has been identified at time of analysis.	HIGH	8.7	0.3%	44
CVE-2026-59645	Unbounded recursion in Bouncy Castle's OER (Octet Encoding Rules) parser enables remote unauthenticated denial-of-service against any Java application processing IEEE 1609.2 V2X messages. Because the IEEE 1609.2 schema is cyclic - an Ieee1609Dot2Data structure can nest inside its own SignedData payload - a few kilobytes of crafted input drive the parser into unbounded recursive descent, terminating in a JVM StackOverflowError. Critically, parsing occurs before signature verification, so no authentication or trust relationship is needed to trigger the crash. No public exploit has been identified at time of analysis, but the patch commit exposes two additional heap-exhaustion vectors alongside the primary recursion flaw, all reachable from the same pre-verification code path.	HIGH	8.7	0.3%	44
CVE-2026-59649	Memory exhaustion in Bouncy Castle for Java's OpenPGP parser enables unauthenticated remote denial of service via a crafted User Attribute subpacket with an oversized length header. All Java applications importing untrusted OpenPGP certificates using bc-java before 1.85, bc-lts-java before 2.73.12, or BC-FJA (FIPS) in affected series are vulnerable to pre-authentication JVM heap exhaustion. No KEV listing or public exploit has been confirmed at time of analysis, but the zero-complexity unauthenticated network attack vector and CVSS 4.0 score of 8.7 signal high operational priority for services that accept OpenPGP certificates from external sources.	HIGH	8.7	0.3%	44
CVE-2026-12852	Heap exhaustion via uncontrolled memory allocation in Bouncy Castle for Java's MLS wire decoder allows remote unauthenticated attackers to crash any application using the bc-java MLS module. The MLSInputStream.readOpaque() method decodes an attacker-supplied Varint length field (up to 0x3FFFFFFF, approximately 1 GiB) and allocates that buffer before verifying the input stream actually contains that many bytes; a handful of concurrent few-byte crafted messages can exhaust the JVM heap. No public exploit has been identified at time of analysis and CISA KEV listing is absent, though the attack is trivially constructable from the published patch and regression test.	HIGH	8.7	0.3%	44

CVE-2026-8763

Certificate name-constraint bypass in Bouncy Castle for Java allows a crafted certificate to escape X.509 permitted/excluded subtree restrictions by appending a trailing dot to an rfc822Name (email) or URI host, or by prepending RDNs ahead of a permitted directoryName. Any relying party using BC's PKIXNameConstraintValidator (via CertPathValidator/CertPathBuilder) to enforce name constraints can be tricked into trusting an identity a constrained CA was never authorized to issue, enabling impersonation and effective authentication bypass. There is no public exploit identified at time of analysis, but the vendor rates it 9.3 (Critical) and a fix is available.

CRITICAL

9.3

0.3%

47

CVE-2026-59638

TLS hostname-verification bypass in the Bouncy Castle for Java JSSE provider (BCJSSE) ships the legacy certificate-CN fallback enabled by default, even though the vendor documentation states it is opt-in and gated behind the org.bouncycastle.jsse.client.checkCnFallback property. Affected are BC-Java before 1.85, BC-LTS before 2.73.12, and BC-FJA (FIPS) TLS module bctls-fips before 1.0.24, 2.0.24 and 2.1.24; a MITM-positioned attacker can present a SAN-less certificate whose Subject CN names the victim host and have it silently accepted, defeating name-constraint protections and enabling interception of TLS traffic (CWE-297). This carries a CVSS 4.0 base of 9.3, but there is no public exploit identified at time of analysis and it is not in CISA KEV.

CRITICAL

9.3

0.3%

47

CVE-2026-59650

Private key recovery in Bouncy Castle for Java (bc-java before 1.85, bc-lts-java before 2.73.12) affects the DH agreement code path, where a peer-supplied public value is exponentiated with the local private key without full range/subgroup validation. A malicious protocol peer can submit small-order or out-of-range Diffie-Hellman elements to mount a small-subgroup confinement attack and, when the local private key is static/reused, gradually recover it via CRT - enabling decryption and impersonation. No public exploit identified at time of analysis; the fix is a vendor-released patch and the vulnerability is not listed in CISA KEV.

CRITICAL

9.3

0.3%

47

CVE-2026-58062

Certificate revocation-check bypass in the Bouncy Castle for Java (bc-java) PKIX provider allows a validly-signed OCSP response issued for one certificate to be accepted as proof-of-status for a different certificate, because the stapled response is not bound to the CertID of the certificate actually being checked. This means a revoked end-entity certificate can pass PKIXRevocationChecker validation when a 'good' OCSP response for another serial (e.g. the CA's) is supplied, defeating revocation enforcement in TLS/PKI clients that rely on OCSP stapling. Affected releases are bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FJA (FIPS) before 2.0.2 and 2.1.3; no public exploit identified at time of analysis and it is not listed in CISA KEV.

CRITICAL

9.3

0.2%

47

CVE-2025-14813

GOST CTR block cipher in Bouncy Castle BC-JAVA processes only the first 255 blocks correctly, causing silent data corruption in encryption/decryption operations for longer messages. Affects BC-JAVA versions 1.59 through 1.83, with fix available in version 1.84. Local attack vector (CVSS AV:L) with critical CVSS 9.4 score reflects potential for both confidentiality and integrity compromise when applications process GOST-encrypted data streams exceeding 255 blocks (~4KB). No KEV listing or public

CRITICAL

9.3

0.0%

47

CVE-2026-5598

Non-constant time comparison operations in the Legion of the Bouncy Castle BC-JAVA cryptographic library (core modules, versions 2.17.3 through 1.83) expose FrodoKEM private keys to timing side-channel attacks, enabling remote unauthenticated attackers to extract cryptographic secrets through statistical analysis of operation timing variations. CVSS 4.0 score of 10.0 reflects maximum confidentiality and integrity impact across system and subsequent contexts. EPSS probability is low (0.04%, 14th percentile) and no active exploitation is confirmed, but SSVC framework rates this as automatable with total technical impact. Vendor patch available in BC-JAVA 1.84.

HIGH

8.9

0.0%

45

CVE-2026-58060

Uncontrolled memory allocation in Bouncy Castle for Java's HSS public-key parser allows remote unauthenticated attackers to exhaust JVM heap memory by supplying a crafted public key with an arbitrarily large HSS level count (L value), causing denial of service during signature verification. All three product lines are affected: bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FIPS (bc-fja) before 2.0.2/2.1.3 depending on series. No public exploit has been identified at time of analysis and no CISA KEV listing exists, but the AV:N/AC:L/PR:N attack profile and Bouncy Castle's ubiquity as a Java crypto dependency make this a credible availability risk for any service accepting external HSS/LMS key material.

HIGH

8.7

0.4%

44

CVE-2026-58059

CPU exhaustion in Bouncy Castle for Java allows remote attackers to cause denial of service by supplying X.500 distinguished name attribute values densely packed with RFC 4514 special characters or leading/trailing spaces. The root cause is a quadratic-time O(n²) escaping algorithm in `IETFUtils.valueToString()` that inserts backslashes into the buffer being actively scanned - triggerable through `X500Name.toString()`, `.equals()`, or `.hashCode()`, methods commonly invoked during TLS certificate and LDAP DN processing. No public exploit has been identified beyond the vendor's own regression test, and this vulnerability is not listed in CISA KEV, though the CVSS 4.0 score of 8.7 with AV:N/PR:N signals meaningful exposure for Internet-facing Java services.

HIGH

8.7

0.3%

44

CVE-2026-8798

Unbounded retry loops in BC-FJA's JNI native entropy layer cause calling threads to hang indefinitely when Intel RDSEED or RDRAND instructions persistently fail, producing a non-interruptible thread-level denial of service in any Java FIPS application backed by bc-fips 2.1.x before 2.1.3. The affected JNI seeding routine re-issues the CPU entropy instruction without any iteration limit whenever the carry flag signals failure - a condition reproducible by hardware entropy source faults, DRBG exhaustion under heavy multi-core contention, or hypervisors that do not forward these Intel instructions to guest VMs. No public exploit code has been identified and the vulnerability is not listed in CISA KEV, but the conditions are routinely present in virtualized environments where hypervisors commonly withhold RDRAND/RDSEED forwarding, making this a realistic operational risk for enterprise Java FIPS deployments in cloud or VM-based infrastructure.

HIGH

8.7

0.3%

44

CVE-2026-59646

Memory exhaustion denial-of-service in Bouncy Castle's DTLS implementation allows remote unauthenticated attackers to crash or degrade Java applications by sending crafted handshake messages with inflated 24-bit length fields. Affected are bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FJA (bctls-fips) before 1.0.24, 2.0.24, or 2.1.24 depending on the deployed branch. The buffer allocation occurs pre-authentication during the DTLS handshake reassembly phase - before any signature or Finished verification - making this exploitable without credentials against any exposed DTLS endpoint. No public exploit code has been identified and the vulnerability is not listed in CISA KEV.

HIGH

8.7

0.3%

44

CVE-2026-59640

Bouncy Castle for Java's OpenPGP session-key decryption path re-exposes the Mister-Zuccherato adaptive-chosen-ciphertext oracle by failing to suppress the legacy CFB 'quick check' on the PKESK/session-key route, enabling an attacker with decryption oracle access to recover plaintext from SEIPD v1 encrypted messages. Affected are bc-java before 1.85, bc-lts-java before 2.73.12, and BC-FJA (bcpg-fips) across the 1.0.X, 2.0.X, and 2.1.X series - three distinct product lines used broadly in enterprise and open-source Java applications. No public exploit or CISA KEV listing has been identified at time of analysis; however, the attack technique is well-established in cryptographic literature dating to the Mister-Zuccherato paper.

HIGH

8.7

0.3%

44

CVE-2026-59644

CPU exhaustion in Bouncy Castle for Java's MLS (Messaging Layer Security) implementation allows a network attacker to trigger unbounded HKDF key-derivation iterations by supplying a crafted 32-bit generation counter in an MLS message. The hash-ratchet in GroupKeySet.get(int generation) advances one HKDF step per skipped generation without any upper bound, so a maximally crafted counter forces up to ~4.29 billion derivation steps on the receiving process. Scored CVSS 4.0 at 8.7 with High availability impact and no authentication prerequisites per vendor scoring; no public exploit code or KEV listing has been identified at time of analysis.

HIGH

8.7

0.3%

44

CVE-2026-59645

Unbounded recursion in Bouncy Castle's OER (Octet Encoding Rules) parser enables remote unauthenticated denial-of-service against any Java application processing IEEE 1609.2 V2X messages. Because the IEEE 1609.2 schema is cyclic - an Ieee1609Dot2Data structure can nest inside its own SignedData payload - a few kilobytes of crafted input drive the parser into unbounded recursive descent, terminating in a JVM StackOverflowError. Critically, parsing occurs before signature verification, so no authentication or trust relationship is needed to trigger the crash. No public exploit has been identified at time of analysis, but the patch commit exposes two additional heap-exhaustion vectors alongside the primary recursion flaw, all reachable from the same pre-verification code path.

HIGH

8.7

0.3%

44

CVE-2026-59649

Memory exhaustion in Bouncy Castle for Java's OpenPGP parser enables unauthenticated remote denial of service via a crafted User Attribute subpacket with an oversized length header. All Java applications importing untrusted OpenPGP certificates using bc-java before 1.85, bc-lts-java before 2.73.12, or BC-FJA (FIPS) in affected series are vulnerable to pre-authentication JVM heap exhaustion. No KEV listing or public exploit has been confirmed at time of analysis, but the zero-complexity unauthenticated network attack vector and CVSS 4.0 score of 8.7 signal high operational priority for services that accept OpenPGP certificates from external sources.

HIGH

8.7

0.3%

44

CVE-2026-12852

Heap exhaustion via uncontrolled memory allocation in Bouncy Castle for Java's MLS wire decoder allows remote unauthenticated attackers to crash any application using the bc-java MLS module. The MLSInputStream.readOpaque() method decodes an attacker-supplied Varint length field (up to 0x3FFFFFFF, approximately 1 GiB) and allocates that buffer before verifying the input stream actually contains that many bytes; a handful of concurrent few-byte crafted messages can exhaust the JVM heap. No public exploit has been identified at time of analysis and CISA KEV listing is absent, though the attack is trivially constructable from the published patch and regression test.

HIGH

8.7

0.3%

44

Severity Breakdown

Monthly CVE Trend

Affected Products (7)

Top Risky CVEs