---
id: "CVE-2026-101356"
kind: "vulnerability"
aliases: ["CVE-2026-101356"]
title: "Apache Tomcat: HTTP/2 async servlets can mix up responses between users"
severity: "critical"
cvss: 9.1
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["http2", "java", "package", "runtime", "self-hosted", "tomcat"]
not_affected_if: ["default-config"]
published_at: "2026-10-20T14:16:55+00:00"
first_seen_at: "2026-10-23T21:57:20+00:00"
updated_at: "2026-10-23T22:39:31+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-101356", "first_seen_at": "2026-10-23T21:57:20+00:00"}]
---

# Apache Tomcat: HTTP/2 async servlets can mix up responses between users

Apache Tomcat mishandles object recycling in HTTP/2 processing of asynchronous servlets, so requests and responses can get mixed up between users. An attacker may receive another user's response or have their request answered with someone else's data.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

Check the Tomcat version: run catalina.sh version and look for 11.0.22 to 11.0.26, 10.1.55 to 10.1.60, or 9.0.118 to 9.0.122.

## Fix

Upgrade to Tomcat 11.0.27, 10.1.61, or 9.0.123 or later.

## Timeline

- 2026-10-23T21:57:20+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101356

## From the sources

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.

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