CVE-2026-24733Network attack vector

Unauthenticated constraint bypass via HTTP/0.9 HEAD

Published Feb 17, 2026 · Updated Feb 17, 2026

Improper input validation in Apache Tomcat allows remote attackers to bypass URI security constraints with an HTTP/0.9 HEAD request. Http11Processor.prepareRequestProtocol accepts non-GET methods for HTTP/0.9, so an invalid HEAD request is handled as a GET after authorization evaluates the permitted HEAD method. Exploitation requires a URI whose constraint allows HEAD but denies GET, and it exposes only content reachable through that mismatched rule.

CVSS severityUnavailable
Unscored
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Apache Tomcat allows remote attackers to bypass URI security constraints with an HTTP/0.9 HEAD request. Http11Processor.prepareRequestProtocol accepts non-GET methods for HTTP/0.9, so an invalid HEAD request is handled as a GET after authorization evaluates the permitted HEAD method. Exploitation requires a URI whose constraint allows HEAD but denies GET, and it exposes only content reachable through that mismatched rule.

The record

CVE
CVE-2026-24733
Published
Feb 17, 2026
Updated
Feb 17, 2026
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 17, 2026Record 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=0 <=8.5.100
  2. Affected versionversion=10.1.0-M1 <=10.1.49
  3. Affected versionversion=11.0.0-M1 <=11.0.14
  4. Affected versionversion=9.0.0.M1 <=9.0.112

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=0 <=8.5.100; version=10.1.0-M1 <=10.1.49; version=11.0.0-M1 <=11.0.14; version=9.0.0.M1 <=9.0.112

Published CVSS scores

2.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U

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-20Improper Input Validation
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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