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High

Apache Tomcat Denial of Service vulnerability

  • Disclosed: 15.06.2020
  • Updated: 11.10.2026 12:22

The HTTP/2 implementation in Apache Tomcat 9.0.0.M1 to 9.0.14 and 8.5.0 to 8.5.37 accepted streams with excessive numbers of SETTINGS frames and also permitted clients to keep streams open without reading/writing request/response data. By keeping streams open for requests that utilised the Servlet API's blocking I/O, clients were able to cause server-side threads to block eventually leading to thread exhaustion and a DoS.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) org.apache.tomcat.embed:tomcat-embed-core >= 9.0.0, < 9.0.16, >= 8.0.0, < 8.5.38 9.0.16, 8.5.38
Java / Kotlin (Maven) org.apache.tomcat:tomcat-coyote >= 9.0.0, < 9.0.16, >= 8.0.0, < 8.5.38 9.0.16, 8.5.38

References

CVSS score 7.5/10
CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE)
CWE-400
Platform
Java / Kotlin (Maven)
Package
org.apache.tomcat.embed:tomcat-embed-core, org.apache.tomcat:tomcat-coyote
Disclosed
15.06.2020
Updated
11.10.2026 12:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-qcxh-w3j9-58qr - CC BY 4.0

Vulnerability history: org.apache.tomcat:tomcat-coyote

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (33) in the archive
Total entries
33
First → latest
06.2020 05.2026
Without a fix
0
Exploited in attacks
1

Severity breakdown

  • Critical 2
  • High 17
  • Medium 13
  • Low 1

Disclosures per year

Severity:
  1. Apache Tomcat - HTTP/2 request headers not validated
    Critical · 9.8 CVE-2026-41293 >= 8.5.0, < 9.0.118, >= 10.1.0-M1, < 10.1.55, >= 11.0.0-M1, < 11.0.22 9.0.118, 10.1.55, 11.0.22
  2. Apache Tomcat has an HTTP Request/Response Smuggling vulnerability
    High · 7.5 CVE-2026-24880 >= 7.0.0, < 9.0.116, >= 10.1.0-M1, < 10.1.52, >= 11.0.0-M1, < 11.0.20 9.0.116, 10.1.52, 11.0.20
  3. Apache Tomcat: Configured cipher preference order not preserved
    High · 7.5 CVE-2026-29129 >= 9.0.114, < 9.0.116, >= 10.1.51, < 10.1.53, >= 11.0.16, < 11.0.20 9.0.116, 10.1.53, 11.0.20
  4. Apache Tomcat has an Improper Input Validation vulnerability
    High · 7.5 CVE-2026-24734 >= 11.0.0-M1, < 11.0.18, >= 10.1.0-M7, < 10.1.52, >= 9.0.83, < 9.0.115 11.0.18, 10.1.52, 9.0.115
  5. Apache Tomcat Improper Resource Shutdown or Release vulnerability
    High · 7.5 CVE-2025-48989 >= 11.0.0-M1, < 11.0.10, >= 10.1.0-M1, < 10.1.44, >= 9.0.0.M1, < 9.0.108 11.0.10, 10.1.44, 9.0.108
  6. Apache Tomcat Coyote vulnerable to Denial of Service via excessive HTTP/2 streams
    High · 7.5 CVE-2025-53506 >= 11.0.0-M1, < 11.0.9, >= 10.1.0-M1, < 10.1.43, >= 9.0.0.M1, < 9.0.107, >= 8.5.0, <= 8.5.100 11.0.9, 10.1.43, 9.0.107
  7. Apache Tomcat Allocation of Resources Without Limits or Throttling vulnerability
    High · 8.6 CVE-2024-38286 >= 11.0.0-M1, < 11.0.0-M21, >= 10.1.0-M1, < 10.1.25, >= 9.0.13, < 9.0.90, >= 8.5.35, <= 8.5.100, >= 7.0.92, <= 7.0.109 11.0.0-M21, 10.1.25, 9.0.90
  8. Apache Tomcat - Denial of Service
    High · 7.5 CVE-2024-34750 >= 11.0.0-M1, < 11.0.0-M21, >= 10.1.0-M1, < 10.1.25, >= 9.0.0-M1, < 9.0.90, >= 8.5.0, <= 8.5.100 11.0.0-M21, 10.1.25, 9.0.90
  9. Apache Tomcat Improper Input Validation vulnerability
    High · 7.5 CVE-2023-46589 >= 11.0.0-M1, < 11.0.0-M11 11.0.0-M11
  10. Apache Tomcat - Fix for CVE-2023-24998 was incomplete
    High · 7.5 CVE-2023-28709 >= 8.5.85, < 8.5.88 8.5.88
  11. Apache Tomcat vulnerable to information leak
    High · 7.5 CVE-2023-34981 >= 8.5.88, < 8.5.89 8.5.89
  12. Apache Commons FileUpload denial of service vulnerability
    High · 7.5 CVE-2023-24998 >= 10.1.0-M1, < 10.1.5, >= 11.0.0-M2, < 11.0.0-M5, >= 8.5.85, < 8.5.88, >= 9.0.0-M1, < 9.0.71 10.1.5, 11.0.0-M5, 8.5.88, 9.0.71
  13. Apache Tomcat may reject request containing invalid Content-Length header
    High · 7.5 CVE-2022-42252 >= 9.0.0-M1, < 9.0.68, >= 10.0.0-M1, < 10.0.27, >= 10.1.0-M1, < 10.1.1 9.0.68, 10.0.27, 10.1.1
  14. Expected Behavior Violation in Apache Tomcat
    Critical · 9.8 CVE-2017-5651 >= 9.0.0.M1, < 9.0.0.M19, >= 8.5.0, < 8.5.13 9.0.0.M19, 8.5.13
  15. Improper Input Validation in Apache Tomcat
    High · 7.1 CVE-2016-6816 >= 9.0.0.M1, < 9.0.0.M12, >= 8.5.0, < 8.5.8, >= 8.0.0RC1, < 8.0.39, >= 7.0.0, < 7.0.73, >= 6.0.0, < 6.0.48 9.0.0.M12, 8.5.8, 8.0.39, 7.0.73, 6.0.48
  16. Exposure of Sensitive Information to an Unauthorized Actor in Apache Tomcat
    High · 7.5 CVE-2020-17527 >= 10.0.0-M1, < 10.0.0-M10, >= 9.0.0-M1, < 9.0.40, >= 8.5.0, < 8.5.60 10.0.0-M10, 9.0.40, 8.5.60
  17. Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat
    High · 7.5 CVE-2020-13934 >= 10.0.0-M1, < 10.0.0-M6, >= 9.0.0.M5, < 9.0.36, >= 8.5.1, < 8.5.56 10.0.0-M6, 9.0.36, 8.5.56
  18. Exposure of Sensitive Information to an Unauthorized Actor in Apache Tomcat
    High · 7.5 CVE-2021-25122 >= 10.0.0-M1, < 10.0.2 10.0.2
  19. Apache Tomcat Denial of Service vulnerability this entry
    High · 7.5 CVE-2019-0199 >= 9.0.0, < 9.0.16, >= 8.0.0, < 8.5.38 9.0.16, 8.5.38

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