CVE-2022-42252Network attack vector

Request smuggling via malformed Content-Length acceptance

Published Nov 1, 2022 · Updated May 6, 2025

HTTP request smuggling in Apache Tomcat allows remote attackers to desynchronize proxied HTTP request streams with a malformed header. Http11InputBuffer ignored an invalid Content-Length line when rejectIllegalHeader was false instead of rejecting the entire request with HTTP 400. Exploitation requires that setting and a reverse proxy that also accepts the malformed request; the setting was the default only in the affected 8.5.x branch.

CVSS severityUnavailable
Unscored
EPSS probability1.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Apache Tomcat allows remote attackers to desynchronize proxied HTTP request streams with a malformed header. Http11InputBuffer ignored an invalid Content-Length line when rejectIllegalHeader was false instead of rejecting the entire request with HTTP 400. Exploitation requires that setting and a reverse proxy that also accepts the malformed request; the setting was the default only in the affected 8.5.x branch.

The record

CVE
CVE-2022-42252
Published
Nov 1, 2022
Updated
May 6, 2025
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-444, CAPEC-33, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 1, 2022CVE publishedPublication date reported by the CVE source.
  2. May 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0-M1 <=10.0.26
  2. Affected versionversion=10.1.0-M1 <=10.1.0
  3. Affected versionversion=8.5.0 <=8.5.82
  4. Affected versionversion=9.0.0-M1 <=9.0.67

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=10.0.0-M1 <=10.0.26; version=10.1.0-M1 <=10.1.0; version=8.5.0 <=8.5.82; version=9.0.0-M1 <=9.0.67

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CAPEC-33HTTP Request Smuggling
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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