CIVETWEB · CVE-2026-124040 · Runtime
NO FIX YET · SEE WHAT TO DO
CivetWeb, an embedded C web server, has a use-after-free in its HTTP/2 handler when built with USE_HTTP2 and enable_http2 turned on. An unauthenticated remote attacker can send a crafted HEADERS frame to change the request method or path seen by access rules, or crash the server.
first public Nov 6, 2026 · 2 sources
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Only builds compiled with USE_HTTP2 and running with enable_http2 on appear exposed, according to the description. Servers that expose CivetWeb to the network and rely on method or path access rules are the most at risk. Deployments without HTTP/2 enabled are not described as affected.
Not affected if default-config, http2-disabled
Who cares c, civetweb, embedded-web-server, http2
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CivetWeb through 1.16, when built with USE_HTTP2 and enable_http2 on, contains a use-after-free vulnerability in handle_http2() that retains freed :method and :path pointers. Unauthenticated remote attackers can send a later HEADERS frame omitting these pseudo-headers to influence request method or path seen by access rules, or crash the server.
This page as .md · .json · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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