Medium
libevent — security advisory
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.
- Products
- libevent
- Affected versions
- 2.0.21-stable-1, 2.0.21-stable-1ubuntu1, 2.0.21-stable-1ubuntu1.14.04.1, 2.0.21-stable-1ubuntu1.14.04.2, 2.0.21-stable-1ubuntu1.14.04.2+esm1, 2.0.21-stable-1ubuntu1.14.04.2+esm2, 2.0.21-stable-2, 2.0.21-stable-2ubuntu0.16.04.1, 2.0.21-stable-2ubuntu0.16.04.1+esm1, 2.0.21-stable-2ubuntu0.16.04.1+esm2, 2.1.11-stable-1, 2.1.11-stable-1ubuntu0.1~esm1, 2.1.11-stable-1ubuntu0.1~esm2, 2.1.11-stable-1~exp0, 2.1.12-stable-1, 2.1.12-stable-10build1, 2.1.12-stable-10build2, 2.1.12-stable-10ubuntu0.1, 2.1.12-stable-10ubuntu0.2, 2.1.12-stable-1build1, 2.1.12-stable-1build2, 2.1.12-stable-1build3, 2.1.12-stable-1ubuntu0.1, 2.1.12-stable-1ubuntu0.2, 2.1.12-stable-9, 2.1.12-stable-9ubuntu2, 2.1.12-stable-9ubuntu2.1, 2.1.12-stable-9ubuntu2.2, 2.1.13-stable-1build1, 2.1.8-stable-4, 2.1.8-stable-4build1, 2.1.8-stable-4ubuntu0.1~esm1, 2.1.8-stable-4ubuntu0.1~esm2
- Fixed versions
- Not specified
- CVEs
- CVE-2026-63379
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:12 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-63379
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
libevent
Fixed versions: Not specified
Complete source record
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],
"modified": "2026-10-17T13:00:32.497468909Z",
"provider": "osv",
"upstream": [
"CVE-2026-63379"
],
"references": [
"https://ubuntu.com/security/CVE-2026-63379",
"https://www.cve.org/CVERecord?id=CVE-2026-63379"
]
},
"related_cves": [
{
"value": "CVE-2026-63379",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 360681,
"published_at": "2026-08-20T18:16:00+00:00"
}