Heap-based Buffer Overflow in Apache HTTP Server ProxyPassReverseCookieMap
CVE-2026-34356 is a heap-based buffer overflow in Apache HTTP Server affecting the ProxyPassReverseCookie* reverse cookie mapping functionality, specifically referenced as ProxyPassReverseCookieMap. The issue affects Apache HTTP Server versions 2.4.0 through 2.4.67. According to the provided content, the flaw can be triggered when httpd interacts with a malicious or untrusted backend server, causing an overflow in internal heap-allocated structures during reverse cookie mapping processing. Apache fixed the issue in the 2.4.x branch in revision r1935008 and released the fix in Apache HTTP Server 2.4.68.
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Exploits
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Recent activity
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A heap-based overflow vulnerability in Apache HTTP Server ProxyPassReverseCookieMap triggered by malicious backend servers.
A heap-related memory corruption vulnerability in Apache HTTP Server's reverse cookie mapping mechanism that allows an untrusted backend to overflow internal structures.
Apache HTTP Server vulnerability involving the ProxyPassReverseCookieMap directive, fixed in version 2.4.68.
Apache HTTP Server vulnerability affecting the ProxyPassReverseCookieMap directive.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.