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Vulnerability record · CVE-2025-65495 · published 24 November 2025

CVE-2025-65495: Libcoap vulnerability

Libcoap · Libcoap

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.

7.5 CVSS 3.1 High EPSS 0.24% · top 86.3% CWE-195 · CWE-195
7.5CVSS 3.1 base score
0.24%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/obgm/libcoap/issues/1744 Issue Tracking
https://github.com/obgm/libcoap/pull/1750 Issue TrackingPatch

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.8CVE-2026-29013Libcoap out-of-bounds read vulnerabilitylibcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c reli…EPSS 0.52%8.2CVE-2025-34468Libcoap stack-based buffer overflow vulnerabilitylibcoap versions up to and including 4.3.5, prior to commit 30db3ea, contain a stack-based buffer overflow in address resolution when attacker-contro…EPSS 0.75%7.8CVE-2024-0962Libcoap stack-based buffer overflow vulnerabilityA vulnerability was found in obgm libcoap 4.3.4. It has been rated as critical. Affected by this issue is the function get_split_entry of the file sr…EPSS 0.76%7.5CVE-2025-65493Libcoap null pointer dereference vulnerabilityNULL pointer dereference in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS/TLS conn…EPSS 0.38%7.5CVE-2025-65494Libcoap null pointer dereference vulnerabilityNULL pointer dereference in get_san_or_cn_from_cert() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of servic…EPSS 0.24%7.5CVE-2024-31031Libcoap integer overflow vulnerabilityAn issue in `coap_pdu.c` in libcoap 4.3.4 allows attackers to cause undefined behavior via a sequence of messages leading to unsigned integer overflo…EPSS 0.87%7.5CVE-2023-30362Libcoap out-of-bounds read vulnerabilityBuffer Overflow vulnerability in coap_send function in libcoap library 4.3.1-103-g52cfd56 fixed in 4.3.1-120-ge242200 allows attackers to obtain sens…EPSS 0.75%6.5CVE-2025-59391Libcoap out-of-bounds read vulnerabilityA memory disclosure vulnerability exists in libcoap's OSCORE configuration parser in libcoap before release-4.3.5-patches. An out-of-bounds read may …EPSS 0.26%

Source: NIST National Vulnerability Database (record CVE-2025-65495), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.