# CVE-2025-53506: Apache Tomcat: DoS via excessive h2 streams at connection start

> CVE-2025-53506: Apache Tomcat: DoS via excessive h2 streams at connection start. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2025-53506
Last updated: 2026-06-17T09:38:20Z

- Published: 2025-07-10 19:14 UTC · Updated: 2026-06-17 09:38 UTC · Assigner: apache
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 2.1%, 82th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-400

## 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.

## Affected vendors and products

- Apache Software Foundation: Apache Tomcat

## Tracked companies

- [Bitbucket](https://rewindex.com/company/bitbucket.md)
- [Jira](https://rewindex.com/company/jira.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2025-53506)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2025-53506)
- [https://lists.apache.org/thread/p09775q0rd185m6zz98krg0fp45j8kr0](https://lists.apache.org/thread/p09775q0rd185m6zz98krg0fp45j8kr0)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2025-53506 · Markdown: https://rewindex.com/cve/CVE-2025-53506.md · JSON: https://rewindex.com/api/v1/cves/CVE-2025-53506 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T04:04:35.931Z