What’s Vulnerable › Vulnerabilities

CVE-2023-45648: Apache Tomcat: Trailer header parsing too lenient

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-10-10 · updated 2026-06-17
• Weakness: CWE-20

Description

Improper Input Validation vulnerability in Apache Tomcat.Tomcat from 11.0.0-M1 through 11.0.0-M11, from 10.1.0-M1 through 10.1.13, from 9.0.0-M1 through 9.0.81 and from 8.5.0 through 8.5.93 did not correctly parse HTTP trailer headers. A specially crafted, invalid trailer header could cause Tomcat to treat a single request as multiple requests leading to the possibility of request smuggling when behind a reverse proxy. Older, EOL versions may also be affected. Users are recommended to upgrade to version 11.0.0-M12 onwards, 10.1.14 onwards, 9.0.81 onwards or 8.5.94 onwards, which fix the issue.

Affected products

• Apache Tomcat: from 8.5.0 before 8.5.94; from 9.0.1 before 9.0.81; from 10.1.1 before 10.1.14; 9.0.0-milestone1, 9.0.0-milestone10, 9.0.0-milestone11, 9.0.0-milestone12, 9.0.0-milestone13, 9.0.0-milestone14 (+52) — fixed in 10.1.14, 8.5.94, 9.0.81
• Debian Linux: 10.0, 11.0, 12.0

How to fix

Upgrade to a fixed version: Apache Tomcat 10.1.14, 8.5.94, 9.0.81. Check the vendor advisory for mitigations.

References

• https://lists.apache.org/thread/2pv8yz1pyp088tsxfb7ogltk9msk0jdp
• http://www.openwall.com/lists/oss-security/2023/10/10/10
• https://lists.apache.org/thread/2pv8yz1pyp088tsxfb7ogltk9msk0jdp
• https://lists.debian.org/debian-lts-announce/2023/10/msg00020.html
• https://security.netapp.com/advisory/ntap-20231103-0007/
• https://www.debian.org/security/2023/dsa-5521
• https://www.debian.org/security/2023/dsa-5522

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