CVE-2026-59099

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreHIGH 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
Trending — 4 sources updated this weekElevated
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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
9.1(high)
EPSS
27.7%
KEV
Not listed

Published

July 2, 2026

Last Modified

July 6, 2026

Advisory Details (5)

Auto-updated Jul 6, 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 61× in last 7d / 61× 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.

  1. 2026-07-07 03:53 UTCEG score recompute
  2. 2026-07-07 03:52 UTCGHSA enrichment
  3. 2026-07-06 23:47 UTCEG score recompute
  4. 2026-07-06 23:47 UTCGHSA enrichment
  5. 2026-07-06 19:43 UTCEG score recompute
  6. 2026-07-06 19:43 UTCGHSA enrichment
  7. 2026-07-06 16:27 UTCEPSS rescore
  8. 2026-07-06 16:27 UTCEPSS rescore
  9. 2026-07-06 15:39 UTCEG score recompute
  10. 2026-07-06 15:39 UTCGHSA enrichment
  11. 2026-07-06 13:07 UTCMITRE cvelistV5CVSS v4 → 9.3
  12. 2026-07-06 11:36 UTCEG score recompute
  13. 2026-07-06 11:36 UTCGHSA enrichment
  14. 2026-07-06 07:31 UTCEG score recompute
  15. 2026-07-06 07:31 UTCGHSA enrichment
  16. 2026-07-06 03:28 UTCEG score recompute
  17. 2026-07-06 03:28 UTCGHSA enrichment
  18. 2026-07-06 02:23 UTCEPSS rescore
  19. 2026-07-06 02:23 UTCEPSS rescore
  20. 2026-07-05 23:16 UTCEG score recompute
  21. 2026-07-05 23:16 UTCGHSA enrichment
  22. 2026-07-05 19:13 UTCEG score recompute
  23. 2026-07-05 19:13 UTCGHSA enrichment
  24. 2026-07-05 15:10 UTCEG score recompute
  25. 2026-07-05 15:10 UTCGHSA enrichment
Show 36 more
  1. 2026-07-05 11:07 UTCEG score recompute
  2. 2026-07-05 11:07 UTCGHSA enrichment
  3. 2026-07-05 07:04 UTCEG score recompute
  4. 2026-07-05 07:03 UTCGHSA enrichment
  5. 2026-07-05 02:59 UTCEG score recompute
  6. 2026-07-05 02:59 UTCGHSA enrichment
  7. 2026-07-05 02:31 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 22:56 UTCEG score recompute
  10. 2026-07-04 22:56 UTCGHSA enrichment
  11. 2026-07-04 18:53 UTCEG score recompute
  12. 2026-07-04 18:52 UTCGHSA enrichment
  13. 2026-07-04 14:49 UTCEG score recompute
  14. 2026-07-04 14:49 UTCGHSA enrichment
  15. 2026-07-04 10:46 UTCEG score recompute
  16. 2026-07-04 10:46 UTCGHSA enrichment
  17. 2026-07-04 06:43 UTCEG score recompute
  18. 2026-07-04 06:43 UTCGHSA enrichment
  19. 2026-07-04 06:31 UTCEPSS rescore
  20. 2026-07-04 06:31 UTCEPSS rescore
  21. 2026-07-04 02:38 UTCEG score recompute
  22. 2026-07-04 02:38 UTCGHSA enrichment
  23. 2026-07-03 22:33 UTCEG score recompute
  24. 2026-07-03 22:33 UTCGHSA enrichment
  25. 2026-07-03 18:28 UTCEG score recompute
  26. 2026-07-03 18:28 UTCGHSA enrichment
  27. 2026-07-03 14:25 UTCEG score recompute
  28. 2026-07-03 14:25 UTCGHSA enrichment
  29. 2026-07-03 10:22 UTCEG score recompute
  30. 2026-07-03 10:21 UTCGHSA enrichment
  31. 2026-07-03 06:18 UTCEG score recompute
  32. 2026-07-03 06:18 UTCGHSA enrichment
  33. 2026-07-03 02:10 UTCEG score recompute
  34. 2026-07-03 02:10 UTCGHSA enrichment
  35. 2026-07-02 22:07 UTCEG score recompute
  36. 2026-07-02 22:06 UTCGHSA enrichment

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 in the National Vulnerability Database on July 2, 2026, with the most recent update on July 6, 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 27.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-59099?
CVE-2026-59099 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-59099?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59099, 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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