CVE-2026-77762 Security Details

CVE ID

CVE-2026-77762

CWE

CWE-362

CVE 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.

Published

Sep 24, 2026

CVSS Score & Severity

6.3Medium

CVSS Vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

EPSS Score

0.464%

Malware

malware

KEV Status

Not in KEV Catalog: No known exploits

Vulnerable Methods

org/apache/coyote/http2/HpackDecoder.emitHeader(Ljava/lang/String;Ljava/lang/String;)V

JVM

org/apache/coyote/http2/HpackDecoder.getHeaderEmitter()Lorg/apache/coyote/http2/HpackDecoder$HeaderEmitter;

JVM

org/apache/coyote/http2/HpackDecoder.setHeaderEmitter(Lorg/apache/coyote/http2/HpackDecoder$HeaderEmitter;)V

JVM

Affected Ecosystems

affected

Source

National Vulnerability Database

References

Apache · AnnouncementPROJECT

GitHub · Advisory · GHSA-28v4-2v86-58ccTHIRD_PARTY