Bug 2539351 (CVE-2026-77756)

Summary: CVE-2026-77756 tomcat: Apache Tomcat: Request smuggling vulnerability can lead to denial of service
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: csutherl, dsoumis, jclere, jwon, pjindal, plodge, rhel-process-autobot, rmaucher, szappis, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Apache Tomcat. This vulnerability, known as HTTP Request/Response Smuggling, occurs when Tomcat processes the transfer-encoding header for an HTTP/1.0 request while operating behind a reverse proxy. A remote attacker could exploit this to cause a denial of service, leading to one user's request failing due to interference from another user's request.
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2543044    
Bug Blocks:    

Description OSIDB Bzimport 2026-09-23 11:31:26 UTC
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.