CVE-2026-59099

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-02. a secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, 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.

Apereo CAS 7.3.0 before 8.0.0-RC6 contains a cryptographic vulnerability that allows remote unauthenticated attackers to recover plaintext conversation state by exploiting AES-GCM initialization vector reuse across the server lifetime. Attackers can collect multiple client-side webflow execution tokens from the unauthenticated login page and perform known-plaintext analysis to decrypt the webflow conversation state due to keystream reuse caused by a fixed all-zero IV paired with the same encryption key.

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
44th
KEV
Not listed

Published

July 2, 2026

Last Modified

July 14, 2026

Advisory Details (5)

Auto-updated Sep 16, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release.
generic

Apereo CAS 7.3.0 < 8.0.0-RC6 - AES-GCM Nonce Reuse Information Disclosure | Advisories | VulnCheck

https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure
generic🟡 PoC Available

oss/cas.md at main · geo-chen/oss · GitHub

https://github.com/geo-chen/oss/blob/main/cas.md
github_release Patch Available

v8.0.0-RC6

Patch available: apereo/cas v8.0.0-RC6 (pre-release)

https://github.com/apereo/cas/releases/tag/v8.0.0-RC6
github_commit Patch Available

commit 22c6f4adf738 (apereo/cas)

Patch available: apereo/cas v8.0.0-RC6 (contains commit 22c6f4adf738)

https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0
generic🟡 PoC Available

CAS Vulnerability Disclosure – Apereo Community Blog

https://apereo.github.io/2026/06/18/vuln/

Vendor Advisories for CVE-2026-59099(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 41× 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 422 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-59099?
CVE-2026-59099 is a critical vulnerability published on July 2, 2026. Apereo CAS 7.3.0 before 8.0.0-RC6 contains a cryptographic vulnerability that allows remote unauthenticated attackers to recover plaintext conversation state by exploiting AES-GCM initialization vector reuse across the server lifetime. Attackers can collect multiple client-side webflow execution…
When was CVE-2026-59099 disclosed?
CVE-2026-59099 was first published on July 2, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59099 actively exploited?
CVE-2026-59099 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-59099?
CVE-2026-59099 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-2026-59099?
A fix for CVE-2026-59099 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59099 are linked in the Vendor Advisories panel on this page.

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