CVE-2026-65637Network attack vectorHinoki check available

Authentication bypass via missing HTTP/2 authority

Published Aug 25, 2026 · Updated Aug 25, 2026

Authentication bypass in Apache Tomcat allows remote attackers to bypass connector-level client certificate checks via HTTP/2. Stream.receivedEndOfHeaders() accepted requests with neither an :authority pseudo-header nor a Host header, leaving serverName unset and evading strict SNI comparison. Exposure requires multiple virtual hosts and client certificate authentication enforced only at the Connector; application-level enforcement is unaffected.

CVSS severityUnavailable
Unscored
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authentication bypass in Apache Tomcat allows remote attackers to bypass connector-level client certificate checks via HTTP/2. Stream.receivedEndOfHeaders() accepted requests with neither an :authority pseudo-header nor a Host header, leaving serverName unset and evading strict SNI comparison. Exposure requires multiple virtual hosts and client certificate authentication enforced only at the Connector; application-level enforcement is unaffected.

The record

CVE
CVE-2026-65637
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=10.1.53 <=10.1.57
  2. Affected versionversion=11.0.20 <=11.0.24
  3. Affected versionversion=9.0.115 <=9.0.120

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=10.1.53 <=10.1.57; version=11.0.20 <=11.0.24; version=9.0.115 <=9.0.120

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo