CVE-2026-63385

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering.

Exploit odds

1.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-20 18:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-26 10:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.3% in the next 30 days (EPSS).
• Severity: 9.2 CRITICAL (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-08-20 18:16 UTC

Last modified

2026-10-26 10:10 UTC

Exploit probability

1.3% · EPSS, next 30 days

Weakness

CWE-444

Record status

Awaiting Analysis

Attack profile CVSS 4.0 · 9.2

Attack vector

Network

Complexity

Low

Attack requirements

Present

Privileges needed

None

User interaction

None

Confidentiality

High

Integrity

High

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-63385.md and follow it. Check whether this project is affected by CVE-2026-63385. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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