CVE-2026-34356Network attack vector

Service crash via reverse-cookie mapping buffer overflow

Published Jun 8, 2026 · Updated Jun 8, 2026

Heap-based buffer overflow in mod_proxy in Apache HTTP Server 2.4.0 through 2.4.67 allows remote attackers to crash the proxy service. The ProxyPassReverseCookieDomain and ProxyPassReverseCookiePath response-rewriting path mishandles a backend-supplied Set-Cookie value, but Apache has not disclosed the specific faulty memory operation. Exploitation requires a configured cookie-rewrite directive and control or compromise of a proxied backend; the reported consequence is service interruption rather than data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in mod_proxy in Apache HTTP Server 2.4.0 through 2.4.67 allows remote attackers to crash the proxy service. The ProxyPassReverseCookieDomain and ProxyPassReverseCookiePath response-rewriting path mishandles a backend-supplied Set-Cookie value, but Apache has not disclosed the specific faulty memory operation. Exploitation requires a configured cookie-rewrite directive and control or compromise of a proxied backend; the reported consequence is service interruption rather than data disclosure or modification.

The record

CVE
CVE-2026-34356
Published
Jun 8, 2026
Updated
Jun 8, 2026
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-122, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 8, 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=2.4.0 <=2.4.67

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=2.4.0 <=2.4.67

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-122Heap-based Buffer Overflow
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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