CVE-2025-65495

moderate-risk

Published 2025-11-24

Integer signedness error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted TLS certificate that causes i2d_X509() to return -1 and be misused as a malloc() size parameter.

Do I need to act?

0.19% 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 7.5/10 High

NETWORK / LOW complexity

Affected Products (1)

Libcoap

Affected Vendors

Libcoap

References (2)

Issue Tracking https://github.com/obgm/libcoap/issues/1744

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

/ 100

moderate-risk

Severity 26/34 · High

Exploitability 1/34 · Minimal

Exposure 5/34 · Minimal