EUVD-2026-39556
GHSA-6q89-vxvr-wgv2
Severity by source
CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Clear
Converted 4.0 AV:A to 3.1 AV:L (no adjacent option in 3.1); AT:P mapped into AC:L; low integrity impact only, no availability or confidentiality.
Primary rating from Vendor (wolfSSL).
CVSS VectorVendor: wolfSSL
Lifecycle Timeline
2DescriptionCVE.org
The PKCS#7 decode path ignores the caller-supplied output buffer size (outputSz), allowing decoded content to be written past the bounds of the provided buffer. This affects wolfSSL 5.9.0 and earlier and was fixed in the 5.9.1 release.
AnalysisAI
Buffer overflow in wolfSSL's PKCS#7 decoder (versions 5.9.0 and earlier) allows attackers with low-privilege account access on an adjacent network to corrupt memory by providing crafted encrypted messages to applications using undersized output buffers in wc_PKCS7_DecodeEncryptedData. Real-world exploitation is severely constrained by requirements for adjacent network access, low privilege, user interaction, and specific attack target conditions, resulting in minimal integrity impact with no availability or confidentiality effects. No public exploit code or active exploitation is known at the time of analysis.
Technical ContextAI
PKCS#7 (Public Key Cryptography Standards #7) defines a standard for cryptographic message syntax used in secure email and other applications. The vulnerability resides in wolfSSL's wc_PKCS7_DecodeEncryptedData function, which implements PKCS#7 encrypted data decoding. The decoder fails to validate the caller-supplied output buffer size parameter (outputSz) before writing decoded content, enabling an out-of-bounds write (CWE-787). The vulnerability is triggered when an application passes a buffer smaller than the decrypted payload size-for example, the test case demonstrates a 496-byte decrypted AES-256-CBC payload written to a 128-byte buffer. wolfSSL is a cryptographic library commonly embedded in IoT devices, industrial control systems, and other resource-constrained environments.
RemediationAI
Upgrade to wolfSSL 5.9.1 or later, which includes the fix from GitHub PR #10116. The patch adds proper output buffer size validation in the PKCS#7 decoder function. For applications unable to upgrade immediately, implement application-level validation to ensure output buffers passed to wc_PKCS7_DecodeEncryptedData are sized larger than the maximum expected decrypted payload. Additionally, audit all code paths calling this function to verify adequate buffer allocation. The underlying flaw is a logic error in the encoder, so no configuration-based workaround exists-upgrading is the primary remediation.
wolfSSL prior to version 3.12.2 provides a weak Bleichenbacher oracle when any TLS cipher suite using RSA key exchange i
A specially crafted x509 certificate can cause a single out of bounds byte overwrite in wolfSSL through 3.10.2 resulting
wolfSSL (formerly CyaSSL) before 3.6.8 allows remote attackers to cause a denial of service (resource consumption or tra
In wolfSSL before 5.5.1, malicious clients can cause a buffer overflow during a TLS 1.3 handshake. Rated high severity (
An issue was discovered in wolfSSL before 5.5.0. Rated high severity (CVSS 7.5), this vulnerability is remotely exploita
wolfSSL 4.3.0 has mulmod code in wc_ecc_mulmod_ex in ecc.c that does not properly resist timing side-channel attacks. Ra
In wolfSSL 4.1.0 through 4.2.0c, there are missing sanity checks of memory accesses in parsing ASN.1 certificate data wh
An issue was discovered in wolfSSL before 4.5.0, when single precision is not employed. Rated high severity (CVSS 7.0).
wolfSSL before 4.5.0 mishandles TLS 1.3 server data in the WAIT_CERT_CR state, within SanityCheckTls13MsgReceived() in t
wolfSSL (formerly CyaSSL) before 3.6.8 does not properly handle faults associated with the Chinese Remainder Theorem (CR
An issue was discovered in wolfSSL before 5.5.0 (when --enable-session-ticket is used); however, only version 5.3.0 is e
wolfSSL 4.6.x through 4.7.x before 4.8.0 does not produce a failure outcome when the serial number in an OCSP request di
Same weakness CWE-787 – Out-of-bounds Write
View allSame technique Buffer Overflow
View allShare
External POC / Exploit Code
Leaving vuln.today