CVE-2026-77762

Apache Tomcat: Stale HPACK emitter injects trailers into recycled pooled Request

Published Sep 23, 2026 CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Apache
Apache apache Tomcat
Vendors & Products Apache
Apache apache Tomcat
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Apache Tomcat: Stale HPACK emitter injects trailers into recycled pooled Request
Weaknesses CWE-362
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apache
Published
Updated
Sep 30, 2026, 2:50 PM
Reserved
Aug 21, 2026, 10:14 AM
Status
Awaiting Analysis
Published
Sep 23, 2026, 12:17 PM
Modified
Sep 30, 2026, 3:22 PM
Severity
Moderate
Public date
Sep 23, 2026, 11:19 AM