Strix
26.1K

CVE-2026-34580

CRITICALCVSS 9.3/10EPSS 0.19%

Last modified

CVE-2026-34580 is a critical-severity vulnerability rated 9.3/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS 4.0
9.3/10

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

EPSS Probability
0.19%

8.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Botan ProjectBotan3.11.0

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-34580?
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.
How severe is CVE-2026-34580?
CVE-2026-34580 has a CVSS score of 9.3/10 (CRITICAL severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.
How do I fix CVE-2026-34580?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-34580?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST