| Name | CVE-2026-42013 |
| Description | A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-4595-1, DSA-6281-1 |
| Debian Bugs | 1135319 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| gnutls28 (PTS) | bullseye | 3.7.1-5+deb11u5 | vulnerable |
| bullseye (security) | 3.7.1-5+deb11u10 | fixed | |
| bookworm | 3.7.9-2+deb12u6 | vulnerable | |
| bookworm (security) | 3.7.9-2+deb12u7 | fixed | |
| trixie | 3.8.9-3+deb13u3 | vulnerable | |
| trixie (security) | 3.8.9-3+deb13u4 | fixed | |
| forky, sid | 3.8.13-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| gnutls28 | source | bullseye | 3.7.1-5+deb11u10 | DLA-4595-1 | ||
| gnutls28 | source | bookworm | 3.7.9-2+deb12u7 | DSA-6281-1 | ||
| gnutls28 | source | trixie | 3.8.9-3+deb13u4 | DSA-6281-1 | ||
| gnutls28 | source | (unstable) | 3.8.13-1 | 1135319 |
https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-8
https://gitlab.com/gnutls/gnutls/-/work_items/1825
https://gitlab.com/gnutls/gnutls/-/issues/1849
Fixed by: https://gitlab.com/gnutls/gnutls/-/commit/29801bef00ecc0f23c0bac4cd333b269cd2c1af4 (3.8.13)