UBUNTU-CVE-2026-44699

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Source
https://ubuntu.com/security/CVE-2026-44699
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-44699
Upstream
Published
2026-05-15T17:16:00Z
Modified
2026-05-20T22:03:09.112046772Z
Severity
  • 9.1 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

LibJWT is a C JSON Web Token Library. From 3.0.0 to 3.3.2, libjwt accepts an RSA JWK that does not contain an alg parameter as the verification key for an HS256/HS384/HS512 token. In the OpenSSL backend, this causes HMAC verification to run with a zero-length key, so an attacker can forge a valid JWT without knowing any secret or RSA private key. This is an algorithm-confusion authentication bypass. It affects applications that load RSA keys from JWKS where alg is omitted, which is valid JWK syntax and common in real deployments, and then choose the verification algorithm from the JWT header, for example in a kid lookup callback. This vulnerability is fixed in 3.3.3.

References

Affected packages

Ubuntu:18.04:LTS
libjwt

Package

Name
libjwt
Purl
pkg:deb/ubuntu/libjwt?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.8.0+dfsg-1
1.8.0+dfsg-2
1.9.0-1
1.9.0-1build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libjwt0",
            "binary_version": "1.9.0-1build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"
Ubuntu:20.04:LTS
libjwt

Package

Name
libjwt
Purl
pkg:deb/ubuntu/libjwt?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.10.2-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libjwt-gnutls0",
            "binary_version": "1.10.2-1"
        },
        {
            "binary_name": "libjwt0",
            "binary_version": "1.10.2-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"
Ubuntu:22.04:LTS
libjwt

Package

Name
libjwt
Purl
pkg:deb/ubuntu/libjwt?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.10.2-1
1.10.2-1build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libjwt-gnutls0",
            "binary_version": "1.10.2-1build1"
        },
        {
            "binary_name": "libjwt0",
            "binary_version": "1.10.2-1build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"
Ubuntu:24.04:LTS
libjwt

Package

Name
libjwt
Purl
pkg:deb/ubuntu/libjwt?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
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": "1.17.0-2build2"
        },
        {
            "binary_name": "libjwt2",
            "binary_version": "1.17.0-2build2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"
Ubuntu:25.10
libjwt

Package

Name
libjwt
Purl
pkg:deb/ubuntu/libjwt?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.17.2-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libjwt-gnutls2",
            "binary_version": "1.17.2-1"
        },
        {
            "binary_name": "libjwt2",
            "binary_version": "1.17.2-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"
Ubuntu:26.04:LTS
libjwt

Package

Name
libjwt
Purl
pkg:deb/ubuntu/libjwt?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.17.2-1
1.17.2-1build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libjwt-gnutls2",
            "binary_version": "1.17.2-1build1"
        },
        {
            "binary_name": "libjwt2",
            "binary_version": "1.17.2-1build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"
libjwt3

Package

Name
libjwt3
Purl
pkg:deb/ubuntu/libjwt3?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.2.2-1
3.2.3-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "jwt-tools",
            "binary_version": "3.2.3-1"
        },
        {
            "binary_name": "libjwt14",
            "binary_version": "3.2.3-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44699.json"