CVE-2026-34582
CRITICALDescription
Botan is a C++ cryptography library. Prior to version 3.11.1, the TLS 1.3 implementation allowed ApplicationData records to be processed prior to the Finished message being received. A server which is attempting to enforce client authentication via certificates can by bypassed by a client which entirely omits Certificate, CertificateVerify, and the Finished message and instead sends application data records. This vulnerability is fixed in 3.11.1.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 14% of all known CVEs.
References
Related Vulnerabilities
Other CWE-841 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2026-67279 | Medium | 6.5 | 2.3% | KEV | Fix |
| CVE-2022-1667 | High | 7.5 | 1.3% | - | Fix |
| CVE-2026-70079 | High | 7.5 | 1.3% | - | Fix |
| CVE-2022-2105 | Critical | 9.4 | 1.1% | - | Fix |
| CVE-2023-4181 | Medium | 5.4 | 1.1% | - | - |
| CVE-2022-2102 | Critical | 9.4 | 0.9% | - | Fix |
Common questions
How do I fix CVE-2026-34582?
Upgrade botan3 on debian 13 to 3.11.0+dfsg-2 or later.
Is CVE-2026-34582 being actively exploited?
Not that we know of. CVE-2026-34582 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.23% is the estimated probability that it will be exploited in the next 30 days. That is higher than 14% of all scored CVEs.
How severe is CVE-2026-34582?
CVE-2026-34582 has a CVSS v3 base score of 9.1, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-34582 affect?
Published advisories record a fix for botan3 (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-24.