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VulnerabilityPublished

CVE-2026-77791: Apache Tomcat · Uncontrolled Resource Consumption

Affects Apache TomcatSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · end of life, no fix coming : replace or isolate Apache Tomcat; no fix will be released.

Data as of 5 Nov 2026, 23:24 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
None coming – the product is end of life
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

No fix will be released: Apache Tomcat is end of life. Replace it, or isolate it from untrusted networks until you can.

Affected software

ProductAffectedFixed in
Apache Software FoundationApache TomcatAffected
  • >=11.0.0-M5 <=11.0.25
  • >=10.1.8 <=10.1.59
  • >=9.0.74 <=9.0.121
  • >=8.5.88 <=8.5.100
Fixed in–
Mavenorg.apache.tomcat/tomcatpkg:maven/org.apache.tomcat/tomcatOther threatsAffected
  • >=11.0.0-M5 <=11.0.25
  • >=10.1.8 <=10.1.59
  • >=9.0.74 <=9.0.121
  • >=8.5.88 <=8.5.100
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Users should upgrade Apache Tomcat to versions 11.0.26, 10.1.60, or 9.0.122, which contain fixes for this vulnerability. Applying these official updates is the recommended and effective mitigation. No other specific mitigations are indicated.

Description

CVE-2026-77791 is an Uncontrolled Resource Consumption vulnerability in Apache Tomcat that allows a denial-of-service (DoS) attack during the sending of WebSocket close messages. This affects multiple Apache Tomcat versions, including 11.0.0-M5 through 11.0.25, 10.1.8 through 10.1.59, 9.0.74 through 9.0.121, and some end-of-life versions 8.5.88 through 8.5.100. Users are advised to upgrade to fixed versions 11.0.26, 10.1.60, or 9.0.122 to mitigate the issue. The vulnerability has a CVSS score of 7.5, indicating high severity.

References

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