CVE-2026-63379

medium Red Hat
CVSS v3 Base Score
6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS Score
0.5%
Exploitation probability in 30 days
Top 58% most likely to be exploited
Attack Characteristics
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Published: August 20, 2026 (17 days ago)
Last Modified: August 20, 2026
Vendor: Red Hat
Fix Available: ✓ Yes
Source: REDHAT

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.

CWE

CWE-444

Affected Products

Red Hat Enterprise Linux 10Red Hat Enterprise Linux 6Red Hat Enterprise Linux 7Red Hat Enterprise Linux 8Red Hat Enterprise Linux 9Red Hat OpenShift Container Platform 4Red Hat Hardened Images

Fix Status

✅ Fix Available

References

🔗 bugzilla.redhat.com 🔗 www.cve.org 🔗 nvd.nist.gov 🔗 github.com 🔗 github.com