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: 0.3%CVSS: 7.5Exploit: 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 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
7.5HIGHmedium confidence
EG Risk
50
EG Risk 50/100

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
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
EPSS PROB
0.3%
EPSS %ILE
15th
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.
redhatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-28498
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6912
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6720
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6568
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6567
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6497
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6309
githubMentions a patch (unverified)🟡 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 / EcosystemFix (by version range) / 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 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(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 / 27× 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 153 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

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 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 0.3% probability of exploitation in the next 30 days (15th percentile of EPSS-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?
A fix for CVE-2026-28498 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-28498 are linked in the Vendor Advisories panel on this page.

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