CVE-2025-65500 Null dereference in n/a

Medium 4.3 Published 24 Nov 2025 Updated 24 Nov 2025

Remote attackers can cause a denial of service in libcoap via a crafted DTLS handshake triggering a null pointer dereference.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2025-65500?

CVE-2025-65500 is a medium-severity vulnerability in n/a, published on 24 Nov 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS handshake that triggers SSL_get_SSL_CTX() to return NULL.

Weakness: CWE-476

Which versions are affected by CVE-2025-65500?

It affects 1 product.

Products include Libcoap Libcoap.

How do I fix CVE-2025-65500?

Upgrade to a fixed version.

Is CVE-2025-65500 being exploited?

There is no known exploitation of CVE-2025-65500 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2025-65500, GHSA-fr67-r843-mwhj, UBUNTU-CVE-2025-65500.