ubuntu-cve-2026-42013
Vulnerability from osv_ubuntu
Published
2026-04-30 00:00
Modified
2026-07-14 18:47
Summary
Details
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.
Severity
8.2 (High)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.4.10-4ubuntu1.9+esm4"
},
{
"binary_name": "guile-gnutls",
"binary_version": "3.4.10-4ubuntu1.9+esm4"
},
{
"binary_name": "libgnutls-openssl27",
"binary_version": "3.4.10-4ubuntu1.9+esm4"
},
{
"binary_name": "libgnutls30",
"binary_version": "3.4.10-4ubuntu1.9+esm4"
},
{
"binary_name": "libgnutlsxx28",
"binary_version": "3.4.10-4ubuntu1.9+esm4"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:16.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.4.10-4ubuntu1.9+esm4?arch=source\u0026distro=esm-infra-legacy/xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.4.10-4ubuntu1.9+esm4"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.3.15-5ubuntu2",
"3.3.18-1ubuntu1",
"3.3.20-1ubuntu1",
"3.4.9-2ubuntu1",
"3.4.10-4ubuntu1",
"3.4.10-4ubuntu1.1",
"3.4.10-4ubuntu1.2",
"3.4.10-4ubuntu1.3",
"3.4.10-4ubuntu1.4",
"3.4.10-4ubuntu1.5",
"3.4.10-4ubuntu1.6",
"3.4.10-4ubuntu1.7",
"3.4.10-4ubuntu1.8",
"3.4.10-4ubuntu1.9",
"3.4.10-4ubuntu1.9+esm1",
"3.4.10-4ubuntu1.9+esm2",
"3.4.10-4ubuntu1.9+esm3"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.5.18-1ubuntu1.6+esm4"
},
{
"binary_name": "libgnutls-dane0",
"binary_version": "3.5.18-1ubuntu1.6+esm4"
},
{
"binary_name": "libgnutls-openssl27",
"binary_version": "3.5.18-1ubuntu1.6+esm4"
},
{
"binary_name": "libgnutls30",
"binary_version": "3.5.18-1ubuntu1.6+esm4"
},
{
"binary_name": "libgnutlsxx28",
"binary_version": "3.5.18-1ubuntu1.6+esm4"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:18.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.5.18-1ubuntu1.6+esm4?arch=source\u0026distro=esm-infra/bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.5.18-1ubuntu1.6+esm4"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.5.8-6ubuntu3",
"3.5.17-1ubuntu1",
"3.5.17-1ubuntu3",
"3.5.18-1ubuntu1",
"3.5.18-1ubuntu1.1",
"3.5.18-1ubuntu1.2",
"3.5.18-1ubuntu1.3",
"3.5.18-1ubuntu1.4",
"3.5.18-1ubuntu1.5",
"3.5.18-1ubuntu1.6",
"3.5.18-1ubuntu1.6+esm1",
"3.5.18-1ubuntu1.6+esm2",
"3.5.18-1ubuntu1.6+esm3"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.6.13-2ubuntu1.12+esm3"
},
{
"binary_name": "guile-gnutls",
"binary_version": "3.6.13-2ubuntu1.12+esm3"
},
{
"binary_name": "libgnutls-dane0",
"binary_version": "3.6.13-2ubuntu1.12+esm3"
},
{
"binary_name": "libgnutls-openssl27",
"binary_version": "3.6.13-2ubuntu1.12+esm3"
},
{
"binary_name": "libgnutls30",
"binary_version": "3.6.13-2ubuntu1.12+esm3"
},
{
"binary_name": "libgnutlsxx28",
"binary_version": "3.6.13-2ubuntu1.12+esm3"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.6.13-2ubuntu1.12+esm3?arch=source\u0026distro=esm-infra/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.13-2ubuntu1.12+esm3"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.6.9-5ubuntu1",
"3.6.9-5ubuntu2",
"3.6.10-5",
"3.6.11.1-2",
"3.6.11.1-2ubuntu2",
"3.6.13-2ubuntu1",
"3.6.13-2ubuntu1.1",
"3.6.13-2ubuntu1.2",
"3.6.13-2ubuntu1.3",
"3.6.13-2ubuntu1.6",
"3.6.13-2ubuntu1.7",
"3.6.13-2ubuntu1.8",
"3.6.13-2ubuntu1.9",
"3.6.13-2ubuntu1.10",
"3.6.13-2ubuntu1.11",
"3.6.13-2ubuntu1.12",
"3.6.13-2ubuntu1.12+esm1",
"3.6.13-2ubuntu1.12+esm2"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.7.3-4ubuntu1.9"
},
{
"binary_name": "guile-gnutls",
"binary_version": "3.7.3-4ubuntu1.9"
},
{
"binary_name": "libgnutls-dane0",
"binary_version": "3.7.3-4ubuntu1.9"
},
{
"binary_name": "libgnutls-openssl27",
"binary_version": "3.7.3-4ubuntu1.9"
},
{
"binary_name": "libgnutls30",
"binary_version": "3.7.3-4ubuntu1.9"
},
{
"binary_name": "libgnutlsxx28",
"binary_version": "3.7.3-4ubuntu1.9"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.7.3-4ubuntu1.9?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.7.3-4ubuntu1.9"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.7.1-5ubuntu1",
"3.7.2-2ubuntu1",
"3.7.2-4ubuntu1",
"3.7.2-5ubuntu1",
"3.7.3-4ubuntu1",
"3.7.3-4ubuntu1.1",
"3.7.3-4ubuntu1.2",
"3.7.3-4ubuntu1.3",
"3.7.3-4ubuntu1.4",
"3.7.3-4ubuntu1.5",
"3.7.3-4ubuntu1.6",
"3.7.3-4ubuntu1.7",
"3.7.3-4ubuntu1.8"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.7.3-4ubuntu1.2+Fips1.1"
},
{
"binary_name": "guile-gnutls",
"binary_version": "3.7.3-4ubuntu1.2+Fips1.1"
},
{
"binary_name": "libgnutls-dane0",
"binary_version": "3.7.3-4ubuntu1.2+Fips1.1"
},
{
"binary_name": "libgnutls-openssl27",
"binary_version": "3.7.3-4ubuntu1.2+Fips1.1"
},
{
"binary_name": "libgnutls30",
"binary_version": "3.7.3-4ubuntu1.2+Fips1.1"
},
{
"binary_name": "libgnutlsxx28",
"binary_version": "3.7.3-4ubuntu1.2+Fips1.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:FIPS-preview:22.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.7.3-4ubuntu1.2+Fips1.1?arch=source\u0026distro=fips-preview/jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.7.3-4ubuntu1.2+Fips1.1"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.7.3-4ubuntu1.9+Fips1"
},
{
"binary_name": "guile-gnutls",
"binary_version": "3.7.3-4ubuntu1.9+Fips1"
},
{
"binary_name": "libgnutls-dane0",
"binary_version": "3.7.3-4ubuntu1.9+Fips1"
},
{
"binary_name": "libgnutls-openssl27",
"binary_version": "3.7.3-4ubuntu1.9+Fips1"
},
{
"binary_name": "libgnutls30",
"binary_version": "3.7.3-4ubuntu1.9+Fips1"
},
{
"binary_name": "libgnutlsxx28",
"binary_version": "3.7.3-4ubuntu1.9+Fips1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:FIPS-updates:22.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.7.3-4ubuntu1.9+Fips1?arch=source\u0026distro=fips-updates/jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.7.3-4ubuntu1.9+Fips1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.7.3-4ubuntu1.2+Fips1.1",
"3.7.3-4ubuntu1.3+Fips1.1",
"3.7.3-4ubuntu1.4+Fips1",
"3.7.3-4ubuntu1.5+Fips1",
"3.7.3-4ubuntu1.6+Fips1",
"3.7.3-4ubuntu1.7+Fips1",
"3.7.3-4ubuntu1.7+Fips1.1",
"3.7.3-4ubuntu1.8+Fips1.1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.8.3-1.1ubuntu3.6"
},
{
"binary_name": "libgnutls-dane0t64",
"binary_version": "3.8.3-1.1ubuntu3.6"
},
{
"binary_name": "libgnutls-openssl27t64",
"binary_version": "3.8.3-1.1ubuntu3.6"
},
{
"binary_name": "libgnutls30t64",
"binary_version": "3.8.3-1.1ubuntu3.6"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.8.3-1.1ubuntu3.6?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.8.3-1.1ubuntu3.6"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.8.1-4ubuntu1",
"3.8.1-4ubuntu6",
"3.8.1-4ubuntu7",
"3.8.3-1ubuntu1",
"3.8.3-1.1ubuntu2",
"3.8.3-1.1ubuntu3",
"3.8.3-1.1ubuntu3.1",
"3.8.3-1.1ubuntu3.2",
"3.8.3-1.1ubuntu3.3",
"3.8.3-1.1ubuntu3.4",
"3.8.3-1.1ubuntu3.5"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.8.3-1.1ubuntu3.6+Fips1.2"
},
{
"binary_name": "libgnutls-dane0t64",
"binary_version": "3.8.3-1.1ubuntu3.6+Fips1.2"
},
{
"binary_name": "libgnutls-openssl27t64",
"binary_version": "3.8.3-1.1ubuntu3.6+Fips1.2"
},
{
"binary_name": "libgnutls30t64",
"binary_version": "3.8.3-1.1ubuntu3.6+Fips1.2"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:FIPS-updates:24.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.8.3-1.1ubuntu3.6+Fips1.2?arch=source\u0026distro=fips-updates/noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.8.3-1.1ubuntu3.6+Fips1.2"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.8.3-1.1ubuntu3.1+Fips1",
"3.8.3-1.1ubuntu3.4+Fips1",
"3.8.3-1.1ubuntu3.4+Fips1.1",
"3.8.3-1.1ubuntu3.5+Fips1.1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.8.9-3ubuntu2.2"
},
{
"binary_name": "libgnutls-dane0t64",
"binary_version": "3.8.9-3ubuntu2.2"
},
{
"binary_name": "libgnutls-openssl27t64",
"binary_version": "3.8.9-3ubuntu2.2"
},
{
"binary_name": "libgnutls30t64",
"binary_version": "3.8.9-3ubuntu2.2"
}
]
},
"package": {
"ecosystem": "Ubuntu:25.10",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.8.9-3ubuntu2.2?arch=source\u0026distro=questing"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.8.9-3ubuntu2.2"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.8.9-2ubuntu3",
"3.8.9-3ubuntu1",
"3.8.9-3ubuntu2",
"3.8.9-3ubuntu2.1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "gnutls-bin",
"binary_version": "3.8.12-2ubuntu1.1"
},
{
"binary_name": "libgnutls-dane0t64",
"binary_version": "3.8.12-2ubuntu1.1"
},
{
"binary_name": "libgnutls-openssl27t64",
"binary_version": "3.8.12-2ubuntu1.1"
},
{
"binary_name": "libgnutls30t64",
"binary_version": "3.8.12-2ubuntu1.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "gnutls28",
"purl": "pkg:deb/ubuntu/gnutls28@3.8.12-2ubuntu1.1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.8.12-2ubuntu1.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.8.9-3ubuntu2",
"3.8.10-3ubuntu1",
"3.8.12-2ubuntu1"
]
}
],
"aliases": [],
"details": "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.",
"id": "UBUNTU-CVE-2026-42013",
"modified": "2026-07-14T18:47:40Z",
"published": "2026-04-30T00:00:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-42013"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-42013"
},
{
"type": "REPORT",
"url": "https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-8"
},
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8284-1"
},
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8539-1"
}
],
"related": [
"USN-8284-1",
"USN-8539-1"
],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-42013"
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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