CVE-2026-27962

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 56% of all CVEs by exploit prediction. 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: epss, secondary
Elevated
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.1Exploit: Elevated riskExposed services: Not assessed

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
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation40% × 40%
Automatability100% × 15%
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

Published

March 16, 2026

Last Modified

September 10, 2026

Advisory Details (11)

Auto-updated Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, redhat.
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-2026-27962 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

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-2026:48085
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
redhat Patch Available
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27962.json

Vendor Advisories for CVE-2026-27962(5)

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

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntupython3-authlib (1.6.7-1ubuntu0.1~esm1) @ resolute2026-09-10ubuntu
redhatquay/quay-rhel9:17849872732026-07-29redhat
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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
python-authlib0.15.4-1, 0.15.4-1+deb11u1
  • every version up to 0.15.4-1+deb11u2: fixed in 0.15.4-1+deb11u2
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
python-authlib1.2.0-1, 1.2.0-1+deb12u1
  • every version up to 1.2.0-1+deb12u2: fixed in 1.2.0-1+deb12u2
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
python-authlib1.6.0-1 ... 1.7.2-2 (13 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
python-authlib1.6.0-1 ... 1.6.8-1 (8 versions)
  • every version up to 1.6.9-1: fixed in 1.6.9-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
authlib0.1 ... 1.6.8 (56 versions)
  • every version up to 1.6.9: fixed in 1.6.9
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 6× in last 7d / 28× 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.

Showing the most recent 100 of 171 total refreshes for this CVE.

  1. 2026-10-05 17:42 UTCEPSS rescore
  2. 2026-10-04 23:21 UTCEPSS rescore
  3. 2026-10-03 14:25 UTCEPSS rescore
  4. 2026-10-01 19:49 UTCEPSS rescore
  5. 2026-09-30 15:03 UTCEPSS rescore
  6. 2026-09-29 19:32 UTCOSV refresh
  7. 2026-09-28 13:51 UTCEPSS rescore
  8. 2026-09-26 15:58 UTCEPSS rescore
  9. 2026-09-26 00:26 UTCEPSS rescore
  10. 2026-09-20 20:15 UTCEPSS rescore
  11. 2026-09-20 20:15 UTCEPSS rescore
  12. 2026-09-18 19:28 UTCEPSS rescore
  13. 2026-09-18 19:27 UTCEPSS rescore
  14. 2026-09-17 19:30 UTCEPSS rescore
  15. 2026-09-16 14:08 UTCEPSS rescore
  16. 2026-09-16 05:15 UTCEPSS rescore
  17. 2026-09-13 16:47 UTCEPSS rescore
  18. 2026-09-12 15:01 UTCEPSS rescore
  19. 2026-09-11 14:52 UTCEPSS rescore
  20. 2026-09-10 13:22 UTCEG score recompute
  21. 2026-09-10 13:22 UTCVendor advisory
  22. 2026-09-10 12:28 UTCEG score recompute
  23. 2026-09-10 12:28 UTCVendor advisory
  24. 2026-09-10 09:34 UTCEPSS rescore
  25. 2026-09-08 22:00 UTCEPSS rescore
Show 75 more
  1. 2026-09-07 16:01 UTCEPSS rescore
  2. 2026-09-06 13:47 UTCEPSS rescore
  3. 2026-09-06 13:47 UTCEPSS rescore
  4. 2026-09-04 05:06 UTCEPSS rescore
  5. 2026-09-02 14:11 UTCEPSS rescore
  6. 2026-09-01 13:53 UTCEPSS rescore
  7. 2026-09-01 04:39 UTCEPSS rescore
  8. 2026-09-01 04:39 UTCEPSS rescore
  9. 2026-08-30 19:17 UTCEPSS rescore
  10. 2026-08-30 01:22 UTCEPSS rescore
  11. 2026-08-28 21:41 UTCEPSS rescore
  12. 2026-08-27 14:25 UTCEPSS rescore
  13. 2026-08-26 14:46 UTCEPSS rescore
  14. 2026-08-25 13:48 UTCEPSS rescore
  15. 2026-08-24 12:27 UTCEG score recompute
  16. 2026-08-24 12:27 UTCVendor advisory
  17. 2026-08-23 00:19 UTCEPSS rescore
  18. 2026-08-21 23:49 UTCEPSS rescore
  19. 2026-08-20 22:55 UTCEPSS rescore
  20. 2026-08-19 17:03 UTCEPSS rescore
  21. 2026-08-18 13:48 UTCEPSS rescore
  22. 2026-08-17 13:47 UTCEPSS rescore
  23. 2026-08-17 12:21 UTCEG score recompute
  24. 2026-08-17 12:21 UTCVendor advisory
  25. 2026-08-17 12:13 UTCEG score recompute
  26. 2026-08-17 12:13 UTCVendor advisory
  27. 2026-08-16 14:56 UTCEPSS rescore
  28. 2026-08-16 11:24 UTCEG score recompute
  29. 2026-08-16 11:24 UTCVendor advisory
  30. 2026-08-16 02:14 UTCEPSS rescore
  31. 2026-08-15 01:30 UTCEPSS rescore
  32. 2026-08-14 23:44 UTCVendor advisory
  33. 2026-08-14 19:59 UTCVendor advisory
  34. 2026-08-14 15:02 UTCVendor advisory
  35. 2026-08-14 11:14 UTCVendor advisory
  36. 2026-08-14 07:30 UTCEG score recompute
  37. 2026-08-14 07:30 UTCVendor advisory
  38. 2026-08-13 22:00 UTCEPSS rescore
  39. 2026-08-13 02:03 UTCVendor advisory
  40. 2026-08-12 22:17 UTCEG score recompute
  41. 2026-08-12 22:17 UTCVendor advisory
  42. 2026-08-12 13:50 UTCEPSS rescore
  43. 2026-08-12 12:39 UTCEG score recompute
  44. 2026-08-12 12:39 UTCVendor advisory
  45. 2026-08-12 12:14 UTCEG score recompute
  46. 2026-08-12 12:14 UTCVendor advisory
  47. 2026-08-12 01:20 UTCVendor advisory
  48. 2026-08-11 21:35 UTCEG score recompute
  49. 2026-08-11 21:35 UTCVendor advisory
  50. 2026-08-11 13:42 UTCEPSS rescore
  51. 2026-08-11 08:38 UTCVendor advisory
  52. 2026-08-11 04:42 UTCEG score recompute
  53. 2026-08-11 04:42 UTCVendor advisory
  54. 2026-08-11 00:00 UTCEPSS rescore
  55. 2026-08-10 12:15 UTCVendor advisory
  56. 2026-08-10 08:13 UTCVendor advisory
  57. 2026-08-10 04:28 UTCVendor advisory
  58. 2026-08-10 00:38 UTCVendor advisory
  59. 2026-08-09 20:53 UTCVendor advisory
  60. 2026-08-09 17:09 UTCEG score recompute
  61. 2026-08-09 17:09 UTCVendor advisory
  62. 2026-08-09 13:46 UTCEPSS rescore
  63. 2026-08-09 13:24 UTCVendor advisory
  64. 2026-08-09 07:06 UTCEG score recompute
  65. 2026-08-09 07:06 UTCVendor advisory
  66. 2026-08-08 16:37 UTCEPSS rescore
  67. 2026-08-08 08:43 UTCVendor advisory
  68. 2026-08-08 04:58 UTCVendor advisory
  69. 2026-08-08 01:13 UTCVendor advisory
  70. 2026-08-07 21:28 UTCVendor advisory
  71. 2026-08-07 17:43 UTCEG score recompute
  72. 2026-08-07 17:43 UTCVendor advisory
  73. 2026-08-06 19:35 UTCEG score recompute
  74. 2026-08-06 19:35 UTCVendor advisory
  75. 2026-08-06 13:46 UTCEPSS rescore

Related CVEs(same product + 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 on March 16, 2026, with the most recent update on September 10, 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 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-27962?
CVE-2026-27962 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-27962?
A fix for CVE-2026-27962 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-27962 are linked in the Vendor Advisories panel on this page.

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