CVE-2026-34059Network attack vector

Heap-memory disclosure via undersized AJP data message

Published May 4, 2026 · Updated May 4, 2026

Buffer over-read in mod_proxy_ajp in Apache HTTP Server 2.4.66 and earlier allows attackers to disclose heap memory via a malformed AJP response. The ajp_parse_data function subtracts required framing bytes from the received message length without first rejecting messages shorter than the AJP data-frame minimum. Exploitation requires mod_proxy_ajp to be loaded and configured to connect to an untrusted or compromised AJP backend; integrity impact and service interruption are not reported.

CVSS severity7.5
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer over-read in mod_proxy_ajp in Apache HTTP Server 2.4.66 and earlier allows attackers to disclose heap memory via a malformed AJP response. The ajp_parse_data function subtracts required framing bytes from the received message length without first rejecting messages shorter than the AJP data-frame minimum. Exploitation requires mod_proxy_ajp to be loaded and configured to connect to an untrusted or compromised AJP backend; integrity impact and service interruption are not reported.

The record

CVE
CVE-2026-34059
Published
May 4, 2026
Updated
May 4, 2026
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-126
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2026CVE publishedPublication date reported by the CVE source.
  2. May 4, 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 <=2.4.66

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=0 <=2.4.66

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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.

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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-126Buffer Over-read

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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