CVE-2026-28498

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 87% 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, nvd
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: Elevated riskExposed: 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 library-level vulnerability was identified in the Authlib Python library concerning the validation of OpenID Connect (OIDC) ID Tokens. Specifically, the internal hash verification logic (_verify_hash) responsible for validating the at_hash (Access Token Hash) and c_hash (Authorization Code Hash) claims exhibits a fail-open behavior when encountering an unsupported or unknown cryptographic algorithm. This flaw allows an attacker to bypass mandatory integrity protections by supplying a forged ID Token with a deliberately unrecognized alg header parameter. The library intercepts the unsupported state and silently returns True (validation passed), inherently violating fundamental cryptographic design principles and direct OIDC specifications. This issue has been patched in version 1.6.9.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

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
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
14%
KEV
Not listed

Published

March 16, 2026

Last Modified

September 10, 2026

Advisory Details (10)

Auto-updated Jul 1, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, redhat.
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-28498
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:6912
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:6720
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:6568
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:6567
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:6497
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:6309
github Patch Available🟡 PoC Available

Fail-Open Cryptographic Verification in Authlib OIDC Hash Binding · Advisory · authlib/authlib · GitHub

https://github.com/authlib/authlib/security/advisories/GHSA-m344-f55w-2m6j
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 b9bb2b25bf8b (authlib/authlib)

Patch available: authlib/authlib v1.6.9 (contains commit b9bb2b25bf8b)

https://github.com/authlib/authlib/commit/b9bb2b25bf8b7e01512d847a95c1749646eaa72b

Vendor Advisories for CVE-2026-28498(7)

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

Patch Availability(7)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython3-authlib (1.6.7-1ubuntu0.1~esm1) @ resolute2026-09-10ubuntu
redhatquay/quay-rhel8:17751691552026-04-07redhat
redhatquay/quay-rhel8:17752530922026-04-06redhat
redhatquay/quay-rhel9:17751692262026-04-03redhat
redhatquay/quay-rhel8:17751692192026-04-03redhat
redhatquay/quay-rhel9:17750694912026-04-02redhat
redhatansible-automation-platform-26/lightspeed-chatbot-rhel9:17744170222026-04-01redhat

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 rangeFixed inDependents
python-authlib0.15.4-1, 0.15.4-1+deb11u10.15.4-1+deb11u2—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
python-authlib1.2.0-1, 1.2.0-1+deb12u11.2.0-1+deb12u2—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
python-authlib1.6.0-1 ... 1.7.2-2 (13 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
python-authlib1.6.0-1 ... 1.6.8-1 (8 versions)1.6.9-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
authlib0.1 ... 1.6.8 (56 versions)1.6.9—

Weakness Classification(3)

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 7× in last 7d / 36× 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 138 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-28498?
CVE-2026-28498 is a high 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 library-level vulnerability was identified in the Authlib Python library concerning the validation of OpenID Connect (OIDC) ID Tokens. Specifically, the internal hash verification logic (verifyhash)…
When was CVE-2026-28498 disclosed?
CVE-2026-28498 was first published in the National Vulnerability Database 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-2026-28498 actively exploited?
CVE-2026-28498 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 86.4% of all scored CVEs.
What is the CVSS score of CVE-2026-28498?
CVE-2026-28498 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-28498?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-28498, 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

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