Description
GnuTLS v3.8.13 does not reject a critical keyUsage extension when it cannot be processed, such as when extnValue is an ASN.1 NULL (05 00) instead of a BIT STRING. NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | gnutls28 | No fix yet | — |
| Debian 13 | gnutls28 | No fix yet | — |
| Debian 12 | gnutls28 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | gnutls28 | No fix yet | — |
| Ubuntu 26.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu 24.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu 22.04 LTS | gnutls28 | No fix yet | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS-updates 24.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu Pro 18.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | gnutls28 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | gnutls26 | No fix yet | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | gnutls | No fix yet | — |
Advisories 1
- WID-SEC-2026-3843 GnuTLS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 8, 2026