obgm libcoap 4.3.5 DTLS src/coap_openssl.c tls_verify_call_back denial of service

Summaryinfo

A vulnerability classified as problematic has been found in obgm libcoap 4.3.5. This issue affects the function tls_verify_call_back of the file src/coap_openssl.c of the component DTLS Handler. Performing a manipulation results in denial of service. This vulnerability is identified as CVE-2025-65499. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in obgm libcoap 4.3.5. This affects the function tls_verify_call_back of the file src/coap_openssl.c of the component DTLS Handler. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2025-65499 since 11/18/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 276674 (Linux Distros Unpatched Vulnerability : CVE-2025-65499), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (276674). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• obgm

Name

• libcoap

Version

• 4.3.5

Website

• Product: https://github.com/obgm/libcoap/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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