CVE-2025-65496

low-risk

Published 2025-11-24

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.

Do I need to act?

0.24% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 4.3/10 Medium

NETWORK / LOW complexity

Affected Products (1)

Libcoap

Affected Vendors

Libcoap

References (2)

Issue Tracking https://github.com/obgm/libcoap/issues/1745

Issue Tracking https://github.com/obgm/libcoap/pull/1750

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low-risk

Severity 18/34 · Moderate

Exploitability 1/34 · Minimal

Exposure 5/34 · Minimal