CVE-2026-63382libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, the libevent evhttp parser in http.c inconsistently handles duplicate Transfer-Encoding headers, comma-separated Transfer-Encoding values, and bare line feeds in chunked framing. evhttp_find_header can select only the first header, evhttp_check_transfer_encoding_ was absent so the previous whole-string comparison fails to recognize valid lists ending in chunked, and evhttp_handle_chunked_read uses EVBUFFER_EOL_CRLF rather than EVBUFFER_EOL_CRLF_STRICT, accepting bare LF chunk terminators. When libevent is deployed behind a proxy that frames the same request differently, an unauthenticated remote attacker can desynchronize request boundaries and smuggle a second request, potentially bypassing access controls or poisoning caches. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
- CVSS
- 9.2 CRITICAL (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:L/SA:N
- Weakness (CWE)
- CWE-444
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Aug 20, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
libevent libevent libevent:libevent (from the name) | from 2.2.0-alpha, < 2.2.2-alpha; before 2.1.13 | CNA record |
References
- https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8jx-refsource-confirm
- https://github.com/libevent/libevent/commit/10abb34b8dc3e1184de315dd261ce4b77563cda6x-refsource-misc
- https://github.com/libevent/libevent/commit/5119ceb00557bf007f9065709e852686f3c0bb6ex-refsource-misc
- https://github.com/libevent/libevent/commit/83ba67373032334559b82409db035dd8c3cc1660x-refsource-misc
- https://github.com/libevent/libevent/commit/ac38703b2d312200c4f967f02936af0118d384a0x-refsource-misc
- https://github.com/libevent/libevent/releases/tag/release-2.1.13-stablex-refsource-misc
- https://github.com/libevent/libevent/releases/tag/release-2.2.2-alphax-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.