UBUNTU-CVE-2026-33996 (CVE-2026-33996)
Vulnerability from osv_ubuntu – Published: 2026-03-27 23:17 – Updated: 2026-05-20 15:27 – Source website
VLAI
Details
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
Severity
5.5 (Medium)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libjwt0",
"binary_version": "1.9.0-1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "libjwt",
"purl": "pkg:deb/ubuntu/libjwt@1.9.0-1build1?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.8.0+dfsg-1",
"1.8.0+dfsg-2",
"1.9.0-1",
"1.9.0-1build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libjwt-gnutls0",
"binary_version": "1.10.2-1"
},
{
"binary_name": "libjwt0",
"binary_version": "1.10.2-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "libjwt",
"purl": "pkg:deb/ubuntu/libjwt@1.10.2-1?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.10.2-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libjwt-gnutls0",
"binary_version": "1.10.2-1build1"
},
{
"binary_name": "libjwt0",
"binary_version": "1.10.2-1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "libjwt",
"purl": "pkg:deb/ubuntu/libjwt@1.10.2-1build1?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.10.2-1",
"1.10.2-1build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libjwt-gnutls2",
"binary_version": "1.17.0-2build2"
},
{
"binary_name": "libjwt2",
"binary_version": "1.17.0-2build2"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "libjwt",
"purl": "pkg:deb/ubuntu/libjwt@1.17.0-2build2?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.10.2-1build1",
"1.17.0-2",
"1.17.0-2build1",
"1.17.0-2build2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libjwt-gnutls2",
"binary_version": "1.17.2-1"
},
{
"binary_name": "libjwt2",
"binary_version": "1.17.2-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:25.10",
"name": "libjwt",
"purl": "pkg:deb/ubuntu/libjwt@1.17.2-1?arch=source\u0026distro=questing"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.17.2-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libjwt-gnutls2",
"binary_version": "1.17.2-1build1"
},
{
"binary_name": "libjwt2",
"binary_version": "1.17.2-1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "libjwt",
"purl": "pkg:deb/ubuntu/libjwt@1.17.2-1build1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.17.2-1",
"1.17.2-1build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "jwt-tools",
"binary_version": "3.2.3-1"
},
{
"binary_name": "libjwt14",
"binary_version": "3.2.3-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "libjwt3",
"purl": "pkg:deb/ubuntu/libjwt3@3.2.3-1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.2.2-1",
"3.2.3-1"
]
}
],
"aliases": [],
"details": "LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the `jwk2key` tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.",
"id": "UBUNTU-CVE-2026-33996",
"modified": "2026-05-20T15:27:23Z",
"published": "2026-03-27T23:17:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-33996"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-33996"
},
{
"type": "REPORT",
"url": "https://github.com/benmcollins/libjwt/security/advisories/GHSA-ph96-hqpc-9f66"
},
{
"type": "REPORT",
"url": "https://github.com/benmcollins/libjwt/commit/cfd890286fa49ae61b534c937c9f0428b5c6034c"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L",
"type": "CVSS_V4"
},
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-33996"
]
}
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Sightings
| Author | Source | Type | Date | Other |
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Nomenclature
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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