CVE-2025-65499
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk21th percentile - higher than 21% of all known CVEs
Summary
Array index 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 DTLS handshake that triggers SSL_get_ex_data_X509_STORE_CTX_idx() to return -1.
Risk Assessment
An attacker could remotely crash the application or service, leading to system unavailability. This may disrupt operations and expose the organization to losses.
Recommendation
Update libcoap to a version that fixes this vulnerability. Implement monitoring for unexpected restarts and DTLS errors.
Other vulnerabilities in OISM libcoap
See all- CVE-2025-65501Medium
Null pointer dereference in coap_dtls_info_callback() in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a DTLS handshake where SSL_get_app_data() returns NULL.
- CVE-2025-65500Medium
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.
- CVE-2025-65495High
In OISM libcoap 4.3.5, the tls_verify_call_back() function in src/coap_openssl.c contains an integer signedness error. A crafted TLS certificate causes i2d_X509() to return -1, which is misused as a malloc() size parameter, enabling a remote denial of service attack.
- CVE-2025-65494High
In OISM libcoap 4.3.5, the get_san_or_cn_from_cert() function in src/coap_openssl.c contains a NULL pointer dereference. A crafted X.509 certificate causes sk_GENERAL_NAME_value() to return NULL, leading to a remote denial of service attack.
Original NVD description (English source)
Array index 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 DTLS handshake that triggers SSL_get_ex_data_X509_STORE_CTX_idx() to return -1.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS