Authlib JWS JWK Header Injection: Signature Verification Bypass

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Summary

CVECVE-2026-27962
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-16 18:16:07 UTC
Updated2026-07-01 13:16:55 UTC
DescriptionAuthlib 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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS: 0.005480000 probability, percentile 0.418360000 (date 2026-07-02)

Problem Types: CWE-347 | CWE-347 CWE-347: Improper Verification of Cryptographic Signature | CWE-347 Improper Verification of Cryptographic Signature

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1[email protected]Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Authlib Authlib All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Authlib Authlib affected < 1.6.9 Not specified
ADP Red Hat Red Hat Quay 3.10 Not specified Not specified
ADP Red Hat Red Hat Quay 3.14 Not specified Not specified
ADP Red Hat Red Hat Quay 3.15 Not specified Not specified
ADP Red Hat Red Hat Quay 3.16 Not specified Not specified
ADP Red Hat Lightspeed Core Not specified Not specified
ADP Red Hat Red Hat Ansible Automation Platform 2 Not specified Not specified
ADP Red Hat Red Hat OpenShift AI RHOAI Not specified Not specified
ADP Red Hat Red Hat Satellite 6 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2026:7314 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:24853 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
github.com/authlib/authlib/releases/tag/v1.6.9 [email protected] github.com Product, Release Notes
access.redhat.com/security/cve/CVE-2026-27962 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27962.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
github.com/authlib/authlib/security/advisories/GHSA-wvwj-cvrp-7pv5 [email protected] github.com Exploit, Mitigation, Vendor Advisory
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
access.redhat.com/errata/RHSA-2026:19375 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
github.com/authlib/authlib/commit/a5d4b2d4c9e46bfa11c82f85fdc2bcc0b50ae681 [email protected] github.com Patch
access.redhat.com/errata/RHSA-2026:5665 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
ADP2026-03-16T18:02:07.041ZReported to Red Hat.
ADP2026-03-16T17:34:38.946ZMade public.

Solutions

ADP: RHSA-2026:5665: Red Hat Quay 3.10

ADP: RHSA-2026:7314: Red Hat Quay 3.14

ADP: RHSA-2026:24853: Red Hat Quay 3.15

ADP: RHSA-2026:19375: Red Hat Quay 3.16

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