CVE-2026-63379
Libevent: HTTP Header smuggling
At a glance
- Source
- NVD
- EPSS
- EPSS 0.71 % · percentile 53 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Awaiting Analysis
Description
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
Weaknesses (CWE)
- CWE-444 — HTTP Request/Response Smuggling
References
- https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6
- https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636
- https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485
- https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
- https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | MEDIUM 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N | GitHub_M |
| CVSS 4.0 | MEDIUM 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/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 | NVD · security-advisories@github.com (Secondary) |
European references
- ENISA EUVD · EUVD-2026-63562
- GCVE · GCVE-0-2026-63379
CERT-FR advisories
- CERTFR-2026-AVI-1378 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1336 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1249 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1233 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| libevent · libevent | affected < 2.1.13 ; affected >= 2.2.0-alpha, < 2.2.2-alpha |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |