CVE-2026-27962

CRITICALPre-NVD 9.19.1
EchelonGraph scoreLOW confidence

This critical-severity CVE scores 9.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: secondary
Elevated
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.1
EG Score
9.1(low)
EG Risk
—
EPSS
42.5%
KEV
Not listed

Published

March 16, 2026

Last Modified

July 20, 2026

Advisory Details (10)

Auto-updated Jun 30, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, redhat.
redhat Patch Available
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27962.json
redhat

2448164 – (CVE-2026-27962) CVE-2026-27962 authlib: Authlib: Authentication bypass due to JWK Header Injection vulnerability

https://bugzilla.redhat.com/show_bug.cgi?id=2448164
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-27962
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:7314
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:5665
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:24853
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:19375
github Patch Available🟡 PoC Available

JWS JWK Header Injection: Signature Verification Bypass · Advisory · authlib/authlib · GitHub

https://github.com/authlib/authlib/security/advisories/GHSA-wvwj-cvrp-7pv5
github_release Patch Available

v1.6.9

Patch available: authlib/authlib v1.6.9

https://github.com/authlib/authlib/releases/tag/v1.6.9
github_commit Patch Available

commit a5d4b2d4c9e4 (authlib/authlib)

Patch available: authlib/authlib v1.6.9 (contains commit a5d4b2d4c9e4)

https://github.com/authlib/authlib/commit/a5d4b2d4c9e46bfa11c82f85fdc2bcc0b50ae681

Vendor Advisories for CVE-2026-27962(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatquay/quay-rhel8:17808913952026-06-09redhat
redhatquay/quay-rhel9:17792040862026-05-19redhat
redhatquay/quay-rhel8:17755121632026-04-09redhat
redhatquay/quay-rhel8:17739710772026-03-24redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
authlib0.1 ... 1.6.8 (56 versions)1.6.9—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 40× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-22 14:08 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
  4. 2026-07-21 15:24 UTCEPSS rescore
  5. 2026-07-20 17:08 UTCEPSS rescore
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 14:31 UTCEPSS rescore
  9. 2026-07-19 02:29 UTCEPSS rescore
  10. 2026-07-18 10:04 UTCEPSS rescore
  11. 2026-07-18 10:04 UTCEPSS rescore
  12. 2026-07-18 06:59 UTCOSV refresh
  13. 2026-07-16 17:03 UTCEPSS rescore
  14. 2026-07-16 17:03 UTCEPSS rescore
  15. 2026-07-15 16:57 UTCEPSS rescore
  16. 2026-07-15 16:57 UTCEPSS rescore
  17. 2026-07-15 02:00 UTCEPSS rescore
  18. 2026-07-15 02:00 UTCEPSS rescore
  19. 2026-07-13 22:30 UTCEPSS rescore
  20. 2026-07-13 06:13 UTCEPSS rescore
  21. 2026-07-13 06:13 UTCEPSS rescore
  22. 2026-07-12 05:46 UTCEPSS rescore
  23. 2026-07-11 08:27 UTCEPSS rescore
  24. 2026-07-09 19:10 UTCEPSS rescore
  25. 2026-07-08 15:15 UTCEPSS rescore
Show 15 more
  1. 2026-07-07 13:46 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-05 02:30 UTCEPSS rescore
  7. 2026-07-04 06:31 UTCEPSS rescore
  8. 2026-07-04 06:31 UTCEPSS rescore
  9. 2026-07-01 15:06 UTCEPSS rescore
  10. 2026-07-01 15:06 UTCEPSS rescore
  11. 2026-06-30 23:22 UTCEPSS rescore
  12. 2026-06-30 23:22 UTCEPSS rescore
  13. 2026-06-30 04:38 UTCEG score recompute
  14. 2026-06-30 04:38 UTCVendor advisory
  15. 2026-06-30 04:31 UTCNVD updatefirst tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-27962?
CVE-2026-27962 is a critical vulnerability published on March 16, 2026. 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…
When was CVE-2026-27962 disclosed?
CVE-2026-27962 was first published in the National Vulnerability Database on March 16, 2026, with the most recent update on July 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27962 actively exploited?
CVE-2026-27962 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 42.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-27962?
CVE-2026-27962 has a CVSS v3 base score of 9.1 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-27962?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27962, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-27962

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