CVE-2025-53506
Uncontrolled Resource Consumption vulnerability in Apache Tomcat if an HTTP/2 client did not acknowledge the initial settings frame that reduces the maximum permitted concurrent streams.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.99%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Uncontrolled Resource Consumption vulnerability in Apache Tomcat if an HTTP/2 client did not acknowledge the initial settings frame that reduces the maximum permitted concurrent streams. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.8, from 10.1.0-M1 through 10.1.42, from 9.0.0.M1 through 9.0.106. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 through 8.5.100. Other EOL versions may also be affected. Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.99% probability · 80th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Affected
- apache/tomcat
- Source
- security@apache.org
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.