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VulnerabilityPublished

CVE-2026-86350: Apache Tomcat · HTTP Request/Response smuggling

Affects Apache TomcatSource CVE Database V5

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Mentioned vulnerabilities

Not known to be exploited · CVSS 9.1 Critical.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Apache Software FoundationApache TomcatAffected
  • >=11.0.22 <=11.0.25
  • >=10.1.55 <=10.1.59
  • >=9.0.118 <=9.0.121
Fixed in–
Mavenorg.apache.tomcat/tomcatpkg:maven/org.apache.tomcat/tomcatOther threatsAffected
  • >=9.0.118 <=9.0.121
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 affected Apache Tomcat instances to versions 9.0.122, 10.1.60, or 11.0.26, which contain the official fix for this vulnerability. No other mitigation steps are indicated by the vendor advisory. Patch status is confirmed with official fixes available.

Description

CVE-2026-86350 is a critical vulnerability in Apache Tomcat involving inconsistent interpretation of HTTP/2 requests, leading to HTTP Request/Response smuggling. This flaw is a regression from a previous fix (CVE-2026-41293) and can cause request header mix-ups. It affects Apache Tomcat versions 9.0.118 through 9.0.121, 10.1.55 through 10.1.59, and 11.0.22 through 11.0.25. Upgrading to versions 9.0.122, 10.1.60, or 11.0.26 resolves the issue.

References

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