CVE-2026-77762

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

Published: Sep 23, 2026Updated: Sep 23, 2026 Sources: CVE List NVDCWE-362

8.1HIGH

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:HAttack Complexity

High

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:HConfidentiality

High

I:HIntegrity

High

A:HAvailability

High

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Weaknesses

CWE-362

Affected Products

Apache Software Foundation

oss-project·USaka apache foundation

Apache TomcatOn-premWeb App

Networking Infrastructure / load-balancer-proxy

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique

Privilege Escalation

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References

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

lists.apache.org

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

openwall.com

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