CVE catalog
CVE-2026-42013
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
- Severity
- High · CVSS 8.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.42% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | gnutls28 | sid | 3.8.13-1 | fixed |
| Debian | gnutls28 | forky | 3.8.13-1 | fixed |
| Debian | gnutls28 | trixie | 3.8.9-3+deb13u4 | fixed |
| Debian | gnutls28 | trixie-security | 3.8.9-3+deb13u4 | fixed |
| Debian | gnutls28 | bookworm | 3.7.9-2+deb12u7 | fixed |
| Debian | gnutls28 | bookworm-security | 3.7.9-2+deb12u7 | fixed |
| Cpe | gnutls28 | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Cpe | gnutls-bin | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Cpe | gnutls-doc | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Cpe | libgnutls-dane0t64 | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Cpe | libgnutls-openssl27t64 | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Cpe | libgnutls28-dev | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Cpe | libgnutls30t64 | Not reported | 3.8.3-1.1ubuntu3.6 | fixed |
| Alpine | gnutls | 3.20 | 3.8.13-r0 | fixed |
| Alpine | gnutls | 3.21 | 3.8.13-r0 | fixed |
| Alpine | gnutls | 3.22 | 3.8.13-r0 | fixed |
| Alpine | gnutls | 3.23 | 3.8.13-r0 | fixed |
| Alpine | gnutls | 3.24 | 3.8.13-r0 | fixed |
| Ubuntu | gnutls28 | pro | 3.8.3-1.1ubuntu3.1+Fips1 | vulnerable |
| Ubuntu | gnutls28 | pro | 3.8.3-1.1ubuntu3.4+Fips1 | vulnerable |
| Ubuntu | gnutls28 | pro | 3.8.3-1.1ubuntu3.4+Fips1.1 | vulnerable |
| Ubuntu | gnutls28 | pro | 3.8.3-1.1ubuntu3.5+Fips1.1 | vulnerable |
| Ubuntu | gnutls28 | pro | 3.8.3-1.1ubuntu3.6+Fips1.2 | fixed |
| Ubuntu | gnutls28 | 22.04 | 3.7.1-5ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.2-2ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.2-4ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.2-5ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.1 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.2 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.3 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.4 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.5 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.6 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.7 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.8 | vulnerable |
| Ubuntu | gnutls28 | 22.04 | 3.7.3-4ubuntu1.9 | fixed |
| Ubuntu | gnutls28 | 24.04 | 3.8.1-4ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.1-4ubuntu6 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.1-4ubuntu7 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu2 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3.1 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3.2 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3.3 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3.4 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3.5 | vulnerable |
| Ubuntu | gnutls28 | 24.04 | 3.8.3-1.1ubuntu3.6 | fixed |
| Ubuntu | gnutls28 | 25.10 | 3.8.9-2ubuntu3 | vulnerable |
| Ubuntu | gnutls28 | 25.10 | 3.8.9-3ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 25.10 | 3.8.9-3ubuntu2 | vulnerable |
| Ubuntu | gnutls28 | 25.10 | 3.8.9-3ubuntu2.1 | vulnerable |
| Ubuntu | gnutls28 | 25.10 | 3.8.9-3ubuntu2.2 | fixed |
| Ubuntu | gnutls28 | 26.04 | 3.8.9-3ubuntu2 | vulnerable |
| Ubuntu | gnutls28 | 26.04 | 3.8.10-3ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 26.04 | 3.8.12-2ubuntu1 | vulnerable |
| Ubuntu | gnutls28 | 26.04 | 3.8.12-2ubuntu1.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | gnutls28 | source | sid | 3.8.13-1 | not yet assigned | Not reported | [1135319] |
| Debian | gnutls28 | source | forky | 3.8.13-1 | not yet assigned | Not reported | [1135319] |
| Debian | gnutls28 | source | trixie | 3.8.9-3+deb13u4 | not yet assigned | Not reported | [1135319] |
| Debian | gnutls28 | source | bookworm | 3.7.9-2+deb12u7 | not yet assigned | Not reported | [1135319] |
| Cpe | gnutls28 | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Cpe | gnutls-bin | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Cpe | gnutls-doc | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Cpe | libgnutls-dane0t64 | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Cpe | libgnutls-openssl27t64 | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Cpe | libgnutls28-dev | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Cpe | libgnutls30t64 | cpe | Not reported | 3.8.3-1.1ubuntu3.6 | Not reported | Not reported | Not reported |
| Alpine | gnutls | apk | 3.20 | 3.8.13-r0 | Not reported | ALPINE-CVE-2026-42013 | Not reported |
| Alpine | gnutls | apk | 3.21 | 3.8.13-r0 | Not reported | ALPINE-CVE-2026-42013 | Not reported |
| Alpine | gnutls | apk | 3.22 | 3.8.13-r0 | Not reported | ALPINE-CVE-2026-42013 | Not reported |
| Alpine | gnutls | apk | 3.23 | 3.8.13-r0 | Not reported | ALPINE-CVE-2026-42013 | Not reported |
| Alpine | gnutls | apk | 3.24 | 3.8.13-r0 | Not reported | ALPINE-CVE-2026-42013 | Not reported |
| Ubuntu | gnutls28 | deb | pro | 3.8.3-1.1ubuntu3.6+Fips1.2 | Not reported | UBUNTU-CVE-2026-42013 | Not reported |
| Ubuntu | gnutls28 | deb | 22.04 | 3.7.3-4ubuntu1.9 | Not reported | UBUNTU-CVE-2026-42013 | Not reported |
| Ubuntu | gnutls28 | deb | 24.04 | 3.8.3-1.1ubuntu3.6 | Not reported | UBUNTU-CVE-2026-42013 | Not reported |
| Ubuntu | gnutls28 | deb | 25.10 | 3.8.9-3ubuntu2.2 | Not reported | UBUNTU-CVE-2026-42013 | Not reported |
| Ubuntu | gnutls28 | deb | 26.04 | 3.8.12-2ubuntu1.1 | Not reported | UBUNTU-CVE-2026-42013 | Not reported |
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [gnutls-bin]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [gnutls-doc]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· all · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· all · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· all · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· all · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [guile-gnutls]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [libgnutls28-dev]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [libgnutls30]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [libgnutls-dane0]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [libgnutls-openssl27]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
- [libgnutlsxx30]Fixed
Source package: [gnutls28]
Details (4)
3.7.9-2+deb12u7· amd64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookwormFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· amd64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
3.7.9-2+deb12u7· arm64 · bookworm-securityFixed · Fixed:
3.7.9-2+deb12u7nvd · gnutls28 · debian · bookworm
Observed:
References
- [https://ftp.suse.com/pub/projects/security/]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-42013]
- [https://osv.dev/vulnerability/ALPINE-CVE-2026-42013]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2026-42013]
- [https://security-tracker.debian.org/tracker/CVE-2026-42013]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42013.json]
- [https://ubuntu.com/security/notices/USN-8284-1]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-3043.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX] · [Ubuntu Security Notices (USN)]