CVE-2025-63651 Use after free in n/a

High 7.5 Published 29 Jan 2026 Updated 3 Feb 2026

Attackers can cause a Denial of Service in the Monkey web server by sending a crafted HTTP request that triggers a use-after-free vulnerability.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-63651?

CVE-2025-63651 is a high-severity use after free vulnerability in n/a, published on 29 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A use-after-free in the mk_string_char_search function (mk_core/mk_string.c) of monkey commit f37e984 allows attackers to cause a Denial of Service (DoS) via sending a crafted HTTP request to the server.

Weakness: CWE-416

Which versions are affected by CVE-2025-63651?

It affects 1 product.

Products include Monkey-Project Monkey.

How do I fix CVE-2025-63651?

No fix has been published for CVE-2025-63651 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2025-63651 being exploited?

There is no known exploitation of CVE-2025-63651 in the wild and no public exploit code.

Sources

Also known as AZL-76457, AZL-76536, GHSA-p9xf-3w58-v7mw.