Unknown severity · Source severity not reportedCVE-2026-101356

Apache Tomcat: HTTP/2 request/response mix-up after error during async processingCVE-2026-101356

Answer in brief

CVE-2026-101356 records a Unknown severity vulnerability in Apache Tomcat: HTTP/2 request/response mix-up after error during async processing. The current sources do not mark it as known exploited. The current feed maps Apache Software Foundation/Apache Tomcat (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 20, 2026Updated Oct 20, 2026Source checked Oct 20, 2026First seen by HOL Oct 20, 2026Material review Oct 20, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Apache Software Foundation/Apache Tomcat (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Apache Software Foundation/Apache Tomcatgeneric	>=11.0.22 <=11.0.26 \|\| >=10.1.55 <=10.1.60 \|\| >=9.0.118 <=9.0.122	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Apache Software Foundation/Apache Tomcat.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Oct 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 20, 2026

Sources and claim methodology

Source referencelists.apache.org

Upstream source description

Incorrect object recycling and re-use vulnerability in Apache Tomcat affecting HTTP/2 processing of asynchronous servlets can trigger request and/or response mix-up between users. This issue affects Apache Tomcat: from 11.0.22 through 11.0.26, from 10.1.55 through 10.1.60, from 9.0.118 through 9.0.122. Users are recommended to upgrade to version 11.0.27, 10.1.61 or 9.0.123, which fixes the issue.

Quoted source text, attributed separately from HOL analysis.