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Botan CVE-2026-34580

| EUVDEUVD-2026-19947 CRITICAL
Improper Certificate Validation (CWE-295)
2026-04-07 GitHub_M
Information Disclosure Botan
9.3
CVSS 4.0 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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:X
SUSE
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Red Hat
9.1 HIGH
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

7
Re-analysis Queued
Apr 17, 2026 - 20:37 vuln.today
cvss_changed
Analysis Updated
Apr 16, 2026 - 05:45 EUVD-patch-fix
executive_summary
Re-analysis Queued
Apr 16, 2026 - 05:29 backfill_euvd_patch
patch_released
Patch available
Apr 16, 2026 - 05:29 EUVD
3.11.1
EUVD ID Assigned
Apr 07, 2026 - 21:31 euvd
EUVD-2026-19947
Analysis Generated
Apr 07, 2026 - 21:31 vuln.today
CVE Published
Apr 07, 2026 - 21:12 nvd
CRITICAL 9.3

DescriptionCVE.org

Botan is a C++ cryptography library. In 3.11.0, the function Certificate_Store::certificate_known had a misleading name; it would return true if any certificate in the store had a DN (and subject key identifier, if set) matching that of the argument. It did not check that the cert it found and the cert it was passed were actually the same certificate. In 3.11.0 an extension of path validation logic was made which assumed that certificate_known only returned true if the certificates were in fact identical. The impact is that if an end entity certificate is presented, and its DN (and subject key identifier, if set) match that of any trusted root, the end entity certificate is accepted immediately as if it itself were a trusted root. , This vulnerability is fixed in 3.11.1.

AnalysisAI

Certificate validation bypass in Botan 3.11.0 allows unauthenticated remote attackers to impersonate trusted certificate authorities by presenting end-entity certificates with matching Distinguished Names and subject key identifiers. The flaw in Certificate_Store::certificate_known incorrectly accepts malicious certificates as trusted roots without verifying actual certificate identity, enabling complete TLS/PKI chain validation bypass. This affects only version 3.11.0 and is fixed in 3.11.1. EPSS data not available; no public exploit identified at time of analysis, though the attack vector is network-accessible with low complexity (CVSS:4.0 AV:N/AC:L/PR:N).

Technical ContextAI

Botan is a widely-used C++ cryptography library providing TLS, X.509, and public key infrastructure capabilities. The vulnerability resides in the Certificate_Store::certificate_known function introduced in version 3.11.0, which performs certificate validation during TLS handshakes and X.509 path building. The function was designed to check if a certificate exists in the trusted store but implemented flawed comparison logic-it matched only the Distinguished Name (DN) and optional Subject Key Identifier (SKI) fields rather than performing cryptographic verification of the entire certificate structure. This represents CWE-295 (Improper Certificate Validation), a critical flaw in PKI trust anchor verification. When path validation logic was extended in 3.11.0 to optimize lookups, it incorrectly assumed certificate_known performed identity verification rather than merely attribute matching. The affected product CPE is cpe:2.3:a:randombit:botan:3.11.0, indicating a single-version regression rather than longstanding architectural weakness.

RemediationAI

Upgrade immediately to Botan version 3.11.1, which corrects the Certificate_Store::certificate_known logic to verify complete certificate identity rather than solely DN and SKI attribute matching. The vendor-released patch is available through standard Botan distribution channels and documented in GitHub Security Advisory GHSA-v782-6fq4-q827 at https://github.com/randombit/botan/security/advisories/GHSA-v782-6fq4-q827. Organizations running version 3.11.0 in production should treat this as an emergency upgrade due to the trivial exploit path and critical impact on TLS security. No workarounds are available; the only effective remediation is version upgrade. For systems unable to immediately upgrade, consider temporarily reverting to Botan 3.10.x stable releases until 3.11.1 deployment is feasible, though this may require code compatibility assessment. Verify patch application by confirming installed version reports 3.11.1 or later and review application logs for any suspicious certificate validation failures that may indicate prior exploitation attempts.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Server 12 SP5 Fixed
SUSE Linux Enterprise Server 12 SP5-LTSS Fixed
SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security Fixed
SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 Fixed
SUSE Linux Enterprise Server for SAP Applications 12 SP5 Fixed

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CVE-2026-34580 vulnerability details – vuln.today
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