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.
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
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.
- CVSS v3
- 9.1
- EG Score
- 9.1(low)
- EPSS
- 41.9%
- KEV
- Not listed
Published
March 16, 2026
Last Modified
July 1, 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
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=2448164redhat Patch Available
redhat Patch Available
redhat Patch Available
redhat Patch Available
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-7pv5github_release Patch Available
v1.6.9
Patch available: authlib/authlib v1.6.9
https://github.com/authlib/authlib/releases/tag/v1.6.9github_commit Patch Available
commit a5d4b2d4c9e4 (authlib/authlib)
Patch available: authlib/authlib v1.6.9 (contains commit a5d4b2d4c9e4)
https://github.com/authlib/authlib/commit/a5d4b2d4c9e46bfa11c82f85fdc2bcc0b50ae681Vendor 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.
- RHSA-2026:24853Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Quay 3.15.5
- RHSA-2026:19375Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Quay 3.16.4
- RHSA-2026:7314Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Quay 3.14.7
- RHSA-2026:5665Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Quay 3.10.19
Patch Availability(4)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| redhat | quay/quay-rhel8:1780891395 | 2026-06-09 | redhat |
| redhat | quay/quay-rhel9:1779204086 | 2026-05-19 | redhat |
| redhat | quay/quay-rhel8:1775512163 | 2026-04-09 | redhat |
| redhat | quay/quay-rhel8:1773971077 | 2026-03-24 | redhat |
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)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| authlib | 0.1 ... 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 11× in last 7d / 14× 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.
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 02:23 UTCEPSS rescore
- 2026-07-06 02:23 UTCEPSS rescore
- 2026-07-05 02:30 UTCEPSS rescore
- 2026-07-04 06:31 UTCEPSS rescore
- 2026-07-04 06:31 UTCEPSS rescore
- 2026-07-01 15:06 UTCEPSS rescore
- 2026-07-01 15:06 UTCEPSS rescore
- 2026-06-30 23:22 UTCEPSS rescore
- 2026-06-30 23:22 UTCEPSS rescore
- 2026-06-30 04:38 UTCEG score recompute
- 2026-06-30 04:38 UTCVendor advisory
- 2026-06-30 04:31 UTCNVD updatefirst tracked
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Same vendor
10 shownredhat
Same CWE
10 shownCWE-347
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 1, 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 41.9% 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
Is Your Infrastructure Affected by CVE-2026-27962?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.