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🛡️ CVE-2025-53506 — tomcat

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-400 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Apache Tomcat: DoS via excessive h2 streams at connection start

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 through 11.0.8, from 10.1.0 through 10.1.42, from 9.0.0 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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2025-53506 is classified as CWE-400: Uncontrolled Resource Consumption. A request can consume memory, CPU or storage without limit, exhausting capacity for everyone else.

Affected software

CVE-2025-53506 is recorded against 3 packages.

  • org.apache.tomcat.embed:tomcat-embed-core (from 11.0.0-M1 up to 11.0.9)
  • org.apache.tomcat:tomcat-coyote (from 8.5.0)
  • tomcat

Timeline and source

Published on 10 July 2025 and last revised on 6 March 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Web)
github.com (Package)
lists.apache.org (Web)
lists.debian.org (Web)
www.openwall.com (Web)

Other advisories for this package

org.apache.tomcat:tomcat-coyote has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-400: Uncontrolled Resource Consumption) in other software:

CVE-2025-53506 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-400
Public Exploit ✅ No
Source OSV
Published 2025-07-10
Updated 2026-08-20
Modified 2026-03-06
Fix URL N/A

Affected Packages

Software From version Fixed in
org.apache.tomcat:tomcat-coyote 8.5.0 —
org.apache.tomcat.embed:tomcat-embed-core 11.0.0-M1 11.0.9
tomcat — —

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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