CVE-2026-77762

EUVD-2026-85227

23.09.2026, 12:17

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.

The following versions were EOL at the time the CVE was created but are
known to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.

Users are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix the issue.

Race Condition

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
apache	CNA	8.1 HIGH	NETWORK	HIGH	NONE	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Early Detection

Affected products identified ahead of NVD analysis through intelligence sources.

Vendor	Product	Version	Source
apache	tomcat	𝑥 ≤ 11.0.25	CNA
apache	tomcat	𝑥 ≤ 10.1.59	CNA
apache	tomcat	9.0.39 ≤ 𝑥 ≤ 9.0.121	CNA
apache	tomcat	8.56.59 ≤ 𝑥 ≤ 8.5.100	CNA

Debian Releases

Debian Product

Codename

tomcat10

bookworm	vulnerable
bookworm (security)	vulnerable
forky	vulnerable
sid	10.1.60-1 fixed
trixie	vulnerable
trixie (security)	vulnerable

tomcat11

forky	vulnerable
sid	vulnerable
trixie	vulnerable
trixie (security)	vulnerable

tomcat9

bookworm	9.0.70-2 fixed
forky	9.0.118-1 fixed
sid	9.0.122-1 fixed
trixie	9.0.95-1 fixed

Common Weakness Enumeration

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.

Vulnerability Media Exposure

[GERMAN] Apache Tomcat: Mehrere Schwachstellen
Ein Angreifer kann mehrere Schwachstellen in Apache Tomcat ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen und um Daten zu manipulieren.
Published: 2026-09-22T22:00:00+00:00

References

https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn

http://www.openwall.com/lists/oss-security/2026/09/23/23