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CVE-2026-77756
Published:September 23, 2026
Updated:September 24, 2026
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.
Affected Packages
https://github.com/apache/tomcat.git (GITHUB):
Affected version(s) >=10.1.0-M1 <10.1.60
Fix Suggestion:
Update to version 10.1.60
https://github.com/apache/tomcat.git (GITHUB):
Affected version(s) >=11.0.0-M1 <11.0.26
Fix Suggestion:
Update to version 11.0.26
https://github.com/apache/tomcat.git (GITHUB):
Affected version(s) >=9.0.47 <9.0.122
Fix Suggestion:
Update to version 9.0.122
org.apache.tomcat:tomcat-coyote (JAVA):
Affected version(s) >=9.0.48 <9.0.122
Fix Suggestion:
Update to version 9.0.122
org.apache.tomcat.embed:tomcat-embed-core (JAVA):
Affected version(s) >=9.0.48 <9.0.122
Fix Suggestion:
Update to version 9.0.122
org.apache.tomcat.experimental:tomcat-embed-programmatic (JAVA):
Affected version(s) >=9.0.48 <9.0.122
Fix Suggestion:
Update to version 9.0.122
org.apache.tomcat:tomcat-coyote (JAVA):
Affected version(s) >=11.0.0-M1 <11.0.26
Fix Suggestion:
Update to version 11.0.26
org.apache.tomcat:tomcat-coyote (JAVA):
Affected version(s) >=10.1.0-M1 <10.1.60
Fix Suggestion:
Update to version 10.1.60
org.apache.tomcat.experimental:tomcat-embed-programmatic (JAVA):
Affected version(s) >=10.1.0-M1 <10.1.60
Fix Suggestion:
Update to version 10.1.60
org.apache.tomcat.experimental:tomcat-embed-programmatic (JAVA):
Affected version(s) >=11.0.0-M1 <11.0.26
Fix Suggestion:
Update to version 11.0.26
org.apache.tomcat.embed:tomcat-embed-core (JAVA):
Affected version(s) >=10.1.0-M1 <10.1.60
Fix Suggestion:
Update to version 10.1.60
org.apache.tomcat.embed:tomcat-embed-core (JAVA):
Affected version(s) >=11.0.0-M1 <11.0.26
Fix Suggestion:
Update to version 11.0.26
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CVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
3.7
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
EPSS
Base Score:
0.26