CVE-2026-15565

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-11. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
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: None knownExposed: 0

A fix is available — apply it.

A flaw was found in Undertow. A remote attacker can cause Out of Memory on websockets endpoint without authentication on any @ServerEndpoint class that has any @OnMessage method. This allows an attacker to cause Denial of Service attack without authentication and using only a standard WebSocket handshake.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
39%
KEV
Not listed

Published

August 11, 2026

Last Modified

August 14, 2026

Advisory Details (2)

Auto-updated Aug 11, 2026
Patch available. Sources: redhat.
redhat

2490628 – (CVE-2026-15565) CVE-2026-15565 undertow: undertow-websockets: Undertow: Pre-Auth DoS on websocket endpoint with @ServerEndpoint class with any @OnMessage method

https://bugzilla.redhat.com/show_bug.cgi?id=2490628
redhat Patch Available

CVE-2026-15565 - 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-2026-15565

Vendor Advisories for CVE-2026-15565(2)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatundertow-websockets-jsr2026-08-11redhat

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.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 44× in last 7d / 65× 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. 2026-08-20 23:55 UTCEG score recompute
  2. 2026-08-20 23:55 UTCVendor advisory
  3. 2026-08-20 23:55 UTCGHSA enrichment
  4. 2026-08-20 22:55 UTCEPSS rescore
  5. 2026-08-20 12:41 UTCVendor advisory
  6. 2026-08-20 12:40 UTCGHSA enrichment
  7. 2026-08-20 01:26 UTCEG score recompute
  8. 2026-08-20 01:26 UTCVendor advisory
  9. 2026-08-20 01:26 UTCGHSA enrichment
  10. 2026-08-19 17:03 UTCEPSS rescore
  11. 2026-08-19 14:11 UTCVendor advisory
  12. 2026-08-19 14:11 UTCGHSA enrichment
  13. 2026-08-19 02:57 UTCVendor advisory
  14. 2026-08-19 02:57 UTCGHSA enrichment
  15. 2026-08-18 15:17 UTCEG score recompute
  16. 2026-08-18 15:17 UTCVendor advisory
  17. 2026-08-18 15:17 UTCGHSA enrichment
  18. 2026-08-18 13:48 UTCEPSS rescore
  19. 2026-08-18 02:23 UTCVendor advisory
  20. 2026-08-18 02:23 UTCGHSA enrichment
  21. 2026-08-17 15:01 UTCEG score recompute
  22. 2026-08-17 15:01 UTCVendor advisory
  23. 2026-08-17 15:01 UTCGHSA enrichment
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-17 03:47 UTCVendor advisory
Show 40 more
  1. 2026-08-17 03:47 UTCGHSA enrichment
  2. 2026-08-16 16:32 UTCEG score recompute
  3. 2026-08-16 16:32 UTCVendor advisory
  4. 2026-08-16 16:32 UTCGHSA enrichment
  5. 2026-08-16 14:56 UTCEPSS rescore
  6. 2026-08-16 05:18 UTCEG score recompute
  7. 2026-08-16 05:18 UTCVendor advisory
  8. 2026-08-16 05:18 UTCGHSA enrichment
  9. 2026-08-16 02:14 UTCEPSS rescore
  10. 2026-08-15 18:05 UTCVendor advisory
  11. 2026-08-15 18:05 UTCGHSA enrichment
  12. 2026-08-15 06:51 UTCEG score recompute
  13. 2026-08-15 06:51 UTCVendor advisory
  14. 2026-08-15 06:51 UTCGHSA enrichment
  15. 2026-08-15 01:30 UTCEPSS rescore
  16. 2026-08-14 19:19 UTCVendor advisory
  17. 2026-08-14 19:19 UTCGHSA enrichment
  18. 2026-08-14 13:32 UTCVendor advisory
  19. 2026-08-14 13:32 UTCGHSA enrichment
  20. 2026-08-14 02:17 UTCEG score recompute
  21. 2026-08-14 02:17 UTCVendor advisory
  22. 2026-08-14 02:17 UTCGHSA enrichment
  23. 2026-08-13 22:00 UTCEPSS rescore
  24. 2026-08-13 15:03 UTCVendor advisory
  25. 2026-08-13 15:03 UTCGHSA enrichment
  26. 2026-08-13 03:49 UTCGHSA enrichment
  27. 2026-08-12 16:35 UTCEG score recompute
  28. 2026-08-12 16:35 UTCGHSA enrichment
  29. 2026-08-12 15:37 UTCEG score recompute
  30. 2026-08-12 15:37 UTCGHSA enrichment
  31. 2026-08-12 13:50 UTCEPSS rescore
  32. 2026-08-12 05:54 UTCGHSA enrichment
  33. 2026-08-11 18:39 UTCEG score recompute
  34. 2026-08-11 18:39 UTCGHSA enrichment
  35. 2026-08-11 18:13 UTCEG score recompute
  36. 2026-08-11 18:13 UTCGHSA enrichment
  37. 2026-08-11 13:42 UTCEPSS rescore
  38. 2026-08-11 09:26 UTCEG score recompute
  39. 2026-08-11 09:13 UTCEG score recompute
  40. 2026-08-11 09:13 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-15565?
CVE-2026-15565 is a high vulnerability published on August 11, 2026. A flaw was found in Undertow. A remote attacker can cause Out of Memory on websockets endpoint without authentication on any @ServerEndpoint class that has any @OnMessage method. This allows an attacker to cause Denial of Service attack without authentication and using only a standard WebSocket…
When was CVE-2026-15565 disclosed?
CVE-2026-15565 was first published in the National Vulnerability Database on August 11, 2026, with the most recent update on August 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-15565 actively exploited?
CVE-2026-15565 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 60.7% of all scored CVEs.
What is the CVSS score of CVE-2026-15565?
CVE-2026-15565 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-15565?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-15565, 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

Explore the affected products and dependency analysis for CVE-2026-15565

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