by Kastro
Paper/Archive/CVE-2026-124040

CVE-2026-124040

civetweb civetweb — CivetWeb through 1.16 HTTP/2 Use-After-Free via Stale Pseudo-Header State

EPSS 0.5%CVSS 9.2
critical.is priorityof 100
36
CVSS 9.2 (CNA)9.2 / 10 × 3027.6Not in CISA KEV+300.0EPSS percentile 44.1.441 × 208.8No public exploit+100.0SSVC exploitation: unknown+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
civetweb≤ 1.16–CNA

Scores by source

VulnCheck (CNA)9.2CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
VulnCheck (CNA)8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

refgithub.com/civetweb/civetweb/issues/1379refgithub.com/civetweb/civetwebwriteupgithub.com/civetweb/civetweb/blob/v1.16/src/http2.inl#L1574-L1581writeupvulncheck.com/advisories/civetweb-through-1.16-http-2-use-after-free-via-stale-pseudo-header-state