CVE-2025-65495: libcoap — Fix

Description

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-195 CWE-195

Affected Products

Vendor	Product	Versions
libcoap	libcoap	All

References

Advisories & Patches

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

Other References

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

Frequently Asked Questions

What is CVE-2025-65495? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-65495? +

CVE-2025-65495 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-65495? +

CVE-2025-65495 affects products from libcoap, specifically: libcoap. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-65495? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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