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VulnerabilityPublished Updated

CVE-2026-34580: randombit botan · Improper Certificate Validation

Affects randombit botanSource CVE Database V5

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Not known to be exploited · CVSS 9.3 Critical : upgrade to 3.11.1 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.

Contested

Critical score, yet low EPSS after six months
EPSS
0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.11.1
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade botan and randombit/botan to 3.11.1.

Affected software

ProductAffectedFixed in
randombitbotanAffected
  • >=3.11.0 <3.11.1
Fixed in
  • 3.11.1
GitHubrandombit/botanpkg:github/randombit/botanOther threatsAffected
  • <3.11.1 >=3.11.0
Fixed in
  • 3.11.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in Botan version 3.11.1. Users should upgrade to version 3.11.1 or later to remediate this vulnerability. Patch status is confirmed by the vendor advisory. No additional mitigation steps are indicated.

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.

References

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