CVE-2026-15565

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM 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: 1%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(medium)
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%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
42%
KEV
Not listed

Published

August 11, 2026

Last Modified

September 18, 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(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatundertow-websockets-jsr2026-08-11redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el9eap2026-08-11redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el7eap2026-08-11redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el8eap2026-08-11redhat

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.

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFixed inDependents
undertow1.3.11-1 ... 2.3.8-2 (56 versions)——

Weakness Classification(1)

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

Additional Vendor Advisories

(3)

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 46× in last 7d / 175× 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 234 total refreshes for this CVE.

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

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 September 18, 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 1% probability of exploitation in the next 30 days, which ranks it in the top 57.5% 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-15565

Explore →

Is Your Infrastructure Affected by CVE-2026-15565?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs