CVE-2026-77756 Security Details

CVE ID

CVE-2026-77756

CWE

CWE-444

CVE Description

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat caused by processing the transfer-encoding header for an HTTP/1.0 request may allow an attacker to cause one request from another user to fail when Tomcat is located behind a reverse proxy. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.47 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.67 through 8.5.100. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 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:N/VA:N/SC:N/SI:N/SA:L

EPSS Score

0.526%

Malware

malware

KEV Status

Not in KEV Catalog: No known exploits

Vulnerable Methods

org/apache/coyote/http11/Http11Processor.prepareInputFilters(Lorg/apache/tomcat/util/http/MimeHeaders;)V

JVMVulnerable params: 0

Affected Ecosystems

affected

Source

National Vulnerability Database

References

Apache · AnnouncementPROJECT

Apache · Security advisoryPROJECT