Raw vector
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:XSummary
CVE-2026-34580 is a critical-severity Improper Certificate Validation (CWE-295) vulnerability in Botan Project Botan. Its CVSS base score is 9.3 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 16th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-17 (Public Key Infrastructure Certificates) and SC-23 (Session Authenticity) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-34580 affects Botan, a C++ cryptography library, specifically version 3.11.0. The vulnerability stems from the Certificate_Store::certificate_known function, which returns true if any certificate in the store matches the distinguished name (DN) and subject key identifier (SKID), if set, of the provided certificate, without verifying that the certificates are identical. An extension to path validation logic in 3.11.0 incorrectly assumed this function only returned true for identical certificates, leading to flawed validation (CWE-295: Improper Certificate Validation). The CVSS v3.1 base score is 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).
An attacker can exploit this remotely with low complexity and no privileges or user interaction by presenting an end-entity certificate whose DN and SKID match those of a trusted root certificate in the store. The end-entity certificate is then accepted as a trusted root, bypassing proper chain validation. This enables integrity violations, such as impersonating trusted entities in TLS handshakes or other PKI-dependent operations that use Botan for certificate path validation.
The vulnerability is fixed in Botan 3.11.1, as detailed in the project's security advisory at https://github.com/randombit/botan/security/advisories/GHSA-v782-6fq4-q827. Security practitioners using Botan 3.11.0 should upgrade to 3.11.1 or later to mitigate the issue.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-19947
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 12 hardening rules · 3 OS baselines
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Mitigating Controls (NIST 800-53 r5) AI
PKI certificate issuance and acquisition under an approved policy establishes the trusted roots and processes needed for correct validation.
Protecting session authenticity depends on cryptographic mechanisms whose trust depends on correct certificate validation.
Requiring confidentiality and integrity protection of transmitted data drives use of properly validated certificates in protocols such as TLS.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Certificate-based authentication of users/services/hardware directly depends on correct validation.
Proper certificate validation is a core mechanism for protecting data-in-transit confidentiality and integrity.
Secure development practices explicitly include implementing correct certificate validation logic.
Assessing authenticity/integrity of acquired software often relies on code-signing certificate validation.
Identity assertions conveyed via certificates require validation to be verified.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Requiring issuance and validation of public-key certificates under an approved policy reduces the chance that certificates with improper validation will be trusted.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (3 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-295
- V-248531 OL 8, for PKI-based authentication, must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor. prevents CWE-295
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
RHEL 7 (2 rules)
- V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
- V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
RHEL 8 (2 rules)
- V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295
- V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-295