CVE-2026-27962

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Source
https://cve.org/CVERecord?id=CVE-2026-27962
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27962.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-27962
Aliases
Downstream
Related
Published
2026-03-16T17:34:38.946Z
Modified
2026-07-16T03:30:55.741585651Z
Severity
  • 9.1 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N CVSS Calculator
Summary
Authlib JWS JWK Header Injection: Signature Verification Bypass
Details

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a JWK Header Injection vulnerability in authlib's JWS implementation allows an unauthenticated attacker to forge arbitrary JWT tokens that pass signature verification. When key=None is passed to any JWS deserialization function, the library extracts and uses the cryptographic key embedded in the attacker-controlled JWT jwk header field. An attacker can sign a token with their own private key, embed the matching public key in the header, and have the server accept the forged token as cryptographically valid — bypassing authentication and authorization entirely. This issue has been patched in version 1.6.9.

Database specific 
{
    "cwe_ids": [
        "CWE-347"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27962.json",
    "cna_assigner": "GitHub_M"
}
References

Affected packages

Git / github.com/authlib/authlib

Affected ranges

Type
GIT
Repo
https://github.com/authlib/authlib
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
9266eaa2227ad7e21dc731b2a4a01909aabd934b
Fixed
a5d4b2d4c9e46bfa11c82f85fdc2bcc0b50ae681
Database specific 
{
    "cpe": "cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "1.6.9"
        }
    ],
    "source": [
        "CPE_RANGE",
        "REFERENCES"
    ]
}

Affected versions

v0.*
v0.1
v0.10
v0.11
v0.12
v0.13
v0.14
v0.14.1
v0.14.2
v0.14.3
v0.15
v0.2
v0.2.1
v0.3
v0.4
v0.4.1
v0.5
v0.5.1
v0.6
v0.7
v0.8
v0.9
v1.*
v1.0.0
v1.0.1
v1.1.0
v1.2.0
v1.2.1
v1.3.0
v1.3.2
v1.4.0
v1.4.1
v1.5.0
v1.5.1
v1.5.2
v1.6.0
v1.6.1
v1.6.2
v1.6.3
v1.6.4
v1.6.5
v1.6.6
v1.6.7
v1.6.8

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27962.json"