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: 0.6%CVSS: 7.5Exploit: None knownExposed services: Not assessed

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
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100CISA SSVC

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%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
47th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 11, 2026

Last Modified

September 25, 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(8)

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
redhateap8-xml-security-0:3.0.6-1.redhat_00001.1.el9eap2026-09-22redhat
redhateap8-xml-security-0:3.0.6-1.redhat_00001.1.el10eap2026-09-22redhat
redhateap8-xml-security-0:3.0.6-1.redhat_00001.1.el8eap2026-09-22redhat
redhatio.undertow/undertow-websockets-jsr:2.2.40.SP3-redhat-000012026-08-11redhat
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
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el9eap2026-08-11redhat

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 rangeFix by version rangeDependents
undertow1.3.11-1 ... 2.3.8-2 (56 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 29× in last 7d / 159× 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 312 total refreshes for this CVE.

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

Related CVEs(same product + 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 on August 11, 2026, with the most recent update on September 25, 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 0.6% probability of exploitation in the next 30 days (47th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-15565?
CVE-2026-15565 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-15565?
A fix for CVE-2026-15565 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-15565 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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