CVE-2026-66299

HIGHNVD 5.37.5▲
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-28. NVD baseline CVSS 5.3; sources differ by 2.2.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
7.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 5.3Exploit: None knownExposed: 0

A fix is available — apply it.

Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example.

This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue.

Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue.

CVSS v3
5.3
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
43%
KEV
Not listed

Published

July 28, 2026

Last Modified

August 27, 2026

Advisory Details (1)

Auto-updated Jul 28, 2026
No patch confirmed yet.
generic
https://lists.apache.org/thread/8owczcc1o8qw1rxmg9gvfk4w2jnh4l5k

Vendor Advisories for CVE-2026-66299(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
redhattomcat11-main-11.0.25-0.1.hum12026-08-18redhat

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

(9 across 4 ecosystems)
Debian:13(3)
PackageVulnerable rangeFixed inDependents
tomcat1010.1.40-1 ... 10.1.55-1~deb13u1 (10 versions)——
tomcat1111.0.11-1 ... 11.0.6-1 (10 versions)——
tomcat9—9.0.70-2—
Debian:14(3)
PackageVulnerable rangeFixed inDependents
tomcat1010.1.40-1 ... 10.1.55-1~deb13u1 (10 versions)——
tomcat1111.0.11-1 ... 11.0.6-1 (10 versions)——
tomcat9—9.0.70-2—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
tomcat1010.1.10-1 ... 10.1.9-1 (36 versions)——
tomcat9—9.0.70-2—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
tomcat99.0.43-1 ... 9.0.70-1 (28 versions)9.0.70-2—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 32× in last 7d / 136× 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 222 total refreshes for this CVE.

  1. 2026-09-15 08:40 UTCEG score recompute
  2. 2026-09-15 08:40 UTCVendor advisory
  3. 2026-09-15 08:40 UTCGHSA enrichment
  4. 2026-09-14 16:21 UTCVendor advisory
  5. 2026-09-14 16:21 UTCGHSA enrichment
  6. 2026-09-14 04:51 UTCVendor advisory
  7. 2026-09-14 04:51 UTCGHSA enrichment
  8. 2026-09-13 17:22 UTCEG score recompute
  9. 2026-09-13 17:22 UTCVendor advisory
  10. 2026-09-13 17:22 UTCGHSA enrichment
  11. 2026-09-13 05:52 UTCVendor advisory
  12. 2026-09-13 05:52 UTCGHSA enrichment
  13. 2026-09-12 18:23 UTCEG score recompute
  14. 2026-09-12 18:23 UTCVendor advisory
  15. 2026-09-12 18:23 UTCGHSA enrichment
  16. 2026-09-12 06:53 UTCVendor advisory
  17. 2026-09-12 06:53 UTCGHSA enrichment
  18. 2026-09-11 19:23 UTCEG score recompute
  19. 2026-09-11 19:23 UTCVendor advisory
  20. 2026-09-11 19:23 UTCGHSA enrichment
  21. 2026-09-11 14:53 UTCEPSS rescore
  22. 2026-09-11 09:37 UTCEPSS rescore
  23. 2026-09-11 07:45 UTCVendor advisory
  24. 2026-09-11 07:45 UTCGHSA enrichment
  25. 2026-09-10 20:13 UTCEG score recompute
Show 75 more
  1. 2026-09-10 20:13 UTCVendor advisory
  2. 2026-09-10 20:13 UTCGHSA enrichment
  3. 2026-09-10 07:43 UTCVendor advisory
  4. 2026-09-10 07:43 UTCGHSA enrichment
  5. 2026-09-09 08:02 UTCEG score recompute
  6. 2026-09-09 08:02 UTCVendor advisory
  7. 2026-09-09 08:02 UTCGHSA enrichment
  8. 2026-09-08 22:01 UTCEPSS rescore
  9. 2026-09-07 20:55 UTCEG score recompute
  10. 2026-09-07 20:55 UTCVendor advisory
  11. 2026-09-07 20:55 UTCGHSA enrichment
  12. 2026-09-07 16:01 UTCEPSS rescore
  13. 2026-09-06 18:27 UTCEG score recompute
  14. 2026-09-06 18:27 UTCVendor advisory
  15. 2026-09-06 18:27 UTCGHSA enrichment
  16. 2026-09-06 13:47 UTCEPSS rescore
  17. 2026-09-06 06:57 UTCVendor advisory
  18. 2026-09-06 06:57 UTCGHSA enrichment
  19. 2026-09-05 19:10 UTCEG score recompute
  20. 2026-09-05 19:10 UTCVendor advisory
  21. 2026-09-05 19:10 UTCGHSA enrichment
  22. 2026-09-05 15:31 UTCEPSS rescore
  23. 2026-09-05 05:32 UTCEG score recompute
  24. 2026-09-05 05:32 UTCVendor advisory
  25. 2026-09-05 05:32 UTCGHSA enrichment
  26. 2026-09-04 12:02 UTCEG score recompute
  27. 2026-09-04 12:02 UTCVendor advisory
  28. 2026-09-04 12:02 UTCGHSA enrichment
  29. 2026-09-04 05:07 UTCEPSS rescore
  30. 2026-09-02 14:12 UTCEPSS rescore
  31. 2026-09-01 22:53 UTCEG score recompute
  32. 2026-09-01 22:53 UTCVendor advisory
  33. 2026-09-01 22:53 UTCGHSA enrichment
  34. 2026-09-01 13:54 UTCEPSS rescore
  35. 2026-09-01 04:40 UTCEPSS rescore
  36. 2026-09-01 00:46 UTCVendor advisory
  37. 2026-09-01 00:46 UTCGHSA enrichment
  38. 2026-08-30 22:35 UTCEG score recompute
  39. 2026-08-30 22:35 UTCVendor advisory
  40. 2026-08-30 22:35 UTCGHSA enrichment
  41. 2026-08-30 19:17 UTCEPSS rescore
  42. 2026-08-30 11:06 UTCEG score recompute
  43. 2026-08-30 11:06 UTCVendor advisory
  44. 2026-08-30 11:06 UTCGHSA enrichment
  45. 2026-08-30 01:22 UTCEPSS rescore
  46. 2026-08-29 23:33 UTCEG score recompute
  47. 2026-08-29 23:33 UTCVendor advisory
  48. 2026-08-29 23:33 UTCGHSA enrichment
  49. 2026-08-28 21:42 UTCEPSS rescore
  50. 2026-08-28 04:12 UTCVendor advisory
  51. 2026-08-28 04:11 UTCGHSA enrichment
  52. 2026-08-27 16:31 UTCEG score recompute
  53. 2026-08-27 16:31 UTCVendor advisory
  54. 2026-08-27 16:31 UTCGHSA enrichment
  55. 2026-08-27 16:26 UTCNVD updateCVSS v3 → 5.3 · severity → MEDIUM
  56. 2026-08-27 11:49 UTCVendor advisory
  57. 2026-08-27 11:49 UTCGHSA enrichment
  58. 2026-08-27 00:20 UTCEG score recompute
  59. 2026-08-27 00:20 UTCVendor advisory
  60. 2026-08-27 00:20 UTCGHSA enrichment
  61. 2026-08-26 14:47 UTCEPSS rescore
  62. 2026-08-26 12:51 UTCVendor advisory
  63. 2026-08-26 12:51 UTCGHSA enrichment
  64. 2026-08-26 01:20 UTCVendor advisory
  65. 2026-08-26 01:20 UTCGHSA enrichment
  66. 2026-08-25 13:51 UTCEG score recompute
  67. 2026-08-25 13:51 UTCVendor advisory
  68. 2026-08-25 13:51 UTCGHSA enrichment
  69. 2026-08-25 13:49 UTCEPSS rescore
  70. 2026-08-25 02:22 UTCVendor advisory
  71. 2026-08-25 02:22 UTCGHSA enrichment
  72. 2026-08-24 14:53 UTCEG score recompute
  73. 2026-08-24 14:53 UTCVendor advisory
  74. 2026-08-24 14:53 UTCGHSA enrichment
  75. 2026-08-24 03:23 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-66299?
CVE-2026-66299 is a high vulnerability published on July 28, 2026. Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web…
When was CVE-2026-66299 disclosed?
CVE-2026-66299 was first published in the National Vulnerability Database on July 28, 2026, with the most recent update on August 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66299 actively exploited?
CVE-2026-66299 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 56.6% of all scored CVEs.
What is the CVSS score of CVE-2026-66299?
CVE-2026-66299 has a CVSS v3 base score of 5.3 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 7.5.
How do I remediate CVE-2026-66299?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66299, 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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