cbcvebase.
CVE-2025-31650
published 2025-04-28

CVE-2025-31650: Improper Input Validation vulnerability in Apache Tomcat. Incorrect error handling for some invalid HTTP priority headers resulted in incomplete clean-up of…

PriorityP268high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EXPLOIT
EPSS
66.93%
99.2th percentile
Improper Input Validation vulnerability in Apache Tomcat. Incorrect error handling for some invalid HTTP priority headers resulted in incomplete clean-up of the failed request which created a memory leak. A large number of such requests could trigger an OutOfMemoryException resulting in a denial of service. This issue affects Apache Tomcat: from 9.0.76 through 9.0.102, from 10.1.10 through 10.1.39, from 11.0.0-M2 through 11.0.5. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.90 though 8.5.100. Users are recommended to upgrade to version 9.0.104, 10.1.40 or 11.0.6 which fix the issue.

Affected

11 ranges
VendorProductVersion rangeFixed in
apachetomcat
apachetomcat>= 10.1.10 < 10.1.4010.1.40
apachetomcat>= 11.0.1 < 11.0.611.0.6
apachetomcat>= 9.0.76 < 9.0.1049.0.104
apache_software_foundationapache_tomcat10.1.10 – 10.1.39
apache_software_foundationapache_tomcat11.0.0-M2 – 11.0.5
apache_software_foundationapache_tomcat8.5.90 – 8.5.100
apache_software_foundationapache_tomcat9.0.76 – 9.0.102
debiantomcat10< tomcat10 10.1.40-1 (bookworm)tomcat10 10.1.40-1 (bookworm)
debiantomcat11< tomcat10 10.1.40-1 (bookworm)tomcat10 10.1.40-1 (bookworm)
debiantomcat9< tomcat10 10.1.40-1 (bookworm)tomcat10 10.1.40-1 (bookworm)

Detection & IOCsextracted from sources · hover to see the quote

  • Detect exploit traffic by matching the 'priority' HTTP/2 header containing malformed values such as negative urgency, non-numeric quality values, integer overflow values, or NaN — characteristic of CVE-2025-31650 DoS attempts.
  • Monitor Apache Tomcat logs (catalina.out) for OutOfMemoryError occurrences, which indicate active exploitation of the memory leak triggered by malformed HTTP/2 PRIORITY_UPDATE frames.
  • This vulnerability requires HTTP/2 to be enabled on the target; detection should focus on HTTP/2 traffic (ALPN h2) to Apache Tomcat instances running versions 9.0.76–9.0.102, 10.1.10–10.1.39, or 11.0.0-M2–11.0.5.
  • The attack is unauthenticated and targets no specific endpoint — any path on the server can be used; detection should not rely on specific URI patterns but instead on the malformed 'priority' header value.
  • ·Exploitation requires HTTP/2 to be active on the Tomcat instance. If HTTP/2 is disabled or not negotiated (ALPN), the server is not vulnerable to this specific attack vector.
  • ·No configuration-level mitigation is available for this CVE; the only fix is upgrading to Apache Tomcat 9.0.104, 10.1.40, or 11.0.6.
  • ·EOL versions 8.5.90 through 8.5.100 are confirmed affected but have no fix available from upstream.

CVSS provenance

nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
osv9.8CRITICAL
vendor_ubuntu9.8CRITICAL
vendor_debian7.5HIGH
vendor_redhat7.5HIGH
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