CVE-2026-63385
Publication date 21 August 2026
Last updated 2 September 2026
Ubuntu priority
Description
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has two HTTP parsing weaknesses in http.c. evhttp_decode_uri_internal decodes percent-encoded %00 bytes into literal NUL characters, which can cause downstream C string operations to truncate a path and bypass validation performed on a different representation. evhttp_header_is_valid_value also accepts obsolete line folding in header values containing carriage return or line feed characters, allowing a proxy and libevent to interpret headers differently and enabling header injection or access control bypass. The CRLF header acceptance is fixed in versions 2.1.13 and 2.2.2-alpha, but the reviewed patches do not clearly remediate the URI NUL-truncation condition.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| libevent | 26.04 LTS resolute |
Fixed 2.1.12-stable-10ubuntu0.1
|
| 24.04 LTS noble |
Fixed 2.1.12-stable-9ubuntu2.1
|
|
| 22.04 LTS jammy |
Fixed 2.1.12-stable-1ubuntu0.1
|
|
| 20.04 LTS focal |
Fixed 2.1.11-stable-1ubuntu0.1~esm1
|
|
| 18.04 LTS bionic |
Fixed 2.1.8-stable-4ubuntu0.1~esm1
|
|
| 16.04 LTS xenial |
Fixed 2.0.21-stable-2ubuntu0.16.04.1+esm1
|
|
| 14.04 LTS trusty |
Fixed 2.0.21-stable-1ubuntu1.14.04.2+esm1
|
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CVSS version: CVSS v4.0
Base score
9.2 · Critical
Vector: 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
References
Related Ubuntu Security Notices (USN)
- USN-8710-1
- libevent vulnerabilities
- 1 September 2026