Description
GnuTLS before 3.1.0 does not verify that the RSA PKCS #1 signature algorithm matches the signature algorithm in the certificate, which allows remote attackers to conduct downgrade attacks via unspecified vectors.
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 7 | gnutls26 | 2.12.20-8+deb7u3 | DSA-3191-1 |
| Debian 6.0 | gnutls26 | 2.8.6-1+squeeze5 | DLA-180-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | gnutls26 | 2.12.23-12ubuntu2.2 | USN-2540-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | gnutls +3 | 2.8.5-18.el6 | RHSA-2015:1457 |
Advisories 4
- RHSA-2015:1457 Red Hat Security Advisory: gnutls security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- USN-2540-1 gnutls26, gnutls28 vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-180-1 gnutls26 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3191-1 gnutls26 - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- http://www.gnutls.org/security.html
- DSA-3191 vendor-advisory
- 73119 vdb-entry
- RHSA-2015:1457 vendor-advisory
- 1032148 vdb-entry