CVE-2022-42252: Apache Tomcat request smuggling via malformed content-length

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-11-01 · updated 2026-06-17
Weakness: CWE-444

Description

If Apache Tomcat 8.5.0 to 8.5.82, 9.0.0-M1 to 9.0.67, 10.0.0-M1 to 10.0.26 or 10.1.0-M1 to 10.1.0 was configured to ignore invalid HTTP headers via setting rejectIllegalHeader to false (the default for 8.5.x only), Tomcat did not reject a request containing an invalid Content-Length header making a request smuggling attack possible if Tomcat was located behind a reverse proxy that also failed to reject the request with the invalid header.

Affected products

Apache Tomcat: from 8.5.0 before 8.5.83; from 9.0.0 before 9.0.68; from 10.0.0 before 10.0.27; from 10.1.0 before 10.1.1 — fixed in 10.0.27, 10.1.1, 8.5.83, 9.0.68

How to fix

Upgrade to a fixed version: Apache Tomcat 10.0.27, 10.1.1, 8.5.83, 9.0.68. Check the vendor advisory for mitigations.

References

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