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Apache Tomcat has an HTTP Request/Response Smuggling vulnerability

High severity GitHub Reviewed Published Apr 9, 2026 to the GitHub Advisory Database • Updated May 20, 2026

Package

maven org.apache.tomcat.embed:tomcat-embed-core (Maven)

Affected versions

>= 7.0.0, < 9.0.116
>= 10.1.0-M1, < 10.1.52
>= 11.0.0-M1, <= 11.0.18

Patched versions

9.0.116
10.1.52
11.0.20
maven org.apache.tomcat:tomcat-coyote (Maven)
>= 7.0.0, < 9.0.116
>= 10.1.0-M1, < 10.1.52
>= 11.0.0-M1, <= 11.0.18
9.0.116
10.1.52
11.0.20

Description

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat via invalid chunk extension.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.18, from 10.1.0-M1 through 10.1.52, from 9.0.0.M1 through 9.0.115, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109.
Other, unsupported versions may also be affected.

Users are recommended to upgrade to version 11.0.20, 10.1.52 or 9.0.116, which fix the issue.

References

Published by the National Vulnerability Database Apr 9, 2026
Published to the GitHub Advisory Database Apr 9, 2026
Reviewed Apr 10, 2026
Last updated May 20, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(47th percentile)

Weaknesses

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. Learn more on MITRE.

CVE ID

CVE-2026-24880

GHSA ID

GHSA-563x-q5rq-57qp

Source code

Credits

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