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🛡️ CVE-2026-66299 — 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 WebSocket chat example

Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example.

This issue affects Apache Tomcat: from 11.0.0 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue.

Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), 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-2026-66299 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-2026-66299 is recorded against 1 package.

  • tomcat

Timeline and source

Published on 17 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

www.openwall.com (Web)
lists.apache.org (Web)
nvd.nist.gov (Web)

Other advisories for this package

tomcat 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:

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 2026-08-17
Updated 2026-08-20
Modified 2026-08-17
Fix URL N/A

Affected Packages

Software From version Fixed in
tomcat — —

Similar Threats

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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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