CVE-2026-78383Network attack vector

Service interruption via blocked AJP body reads

Published Sep 23, 2026 · Updated Sep 23, 2026

Resource exhaustion in Apache Tomcat allows remote attackers to interrupt service through a crafted bodyless AJP request. AjpProcessor.finishResponse tries to read and discard an advertised but absent request body even after an error, leaving the processing thread blocked. Exposure requires an enabled, reachable AJP connector; repeated requests can pin the connector's thread pool and prevent it from serving legitimate traffic.

CVSS severityUnavailable
Unscored
EPSS probability0.38%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Apache Tomcat allows remote attackers to interrupt service through a crafted bodyless AJP request. AjpProcessor.finishResponse tries to read and discard an advertised but absent request body even after an error, leaving the processing thread blocked. Exposure requires an enabled, reachable AJP connector; repeated requests can pin the connector's thread pool and prevent it from serving legitimate traffic.

The record

CVE
CVE-2026-78383
Published
Sep 23, 2026
Updated
Sep 23, 2026
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 23, 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=10.1.0-M1 <=10.1.59
  2. Affected versionversion=11.0.0-M1 <=11.0.25
  3. Affected versionversion=7.0.0 <=7.0.109
  4. Affected versionversion=8.5.0 <=8.5.100
  5. Affected versionversion=9.0.0.M1 <=9.0.121

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=10.1.0-M1 <=10.1.59; version=11.0.0-M1 <=11.0.25; version=7.0.0 <=7.0.109; version=8.5.0 <=8.5.100; version=9.0.0.M1 <=9.0.121

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

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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