libcoap up to 4.3.5 Proxy Request stack-based overflow

Summaryinfo

A vulnerability was found in libcoap up to 4.3.5. It has been rated as critical. This affects an unknown part of the component Proxy Request Handler. Performing a manipulation results in stack-based overflow. This vulnerability is reported as CVE-2025-34468. The attack is possible to be carried out remotely. No exploit exists. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability was found in libcoap up to 4.3.5. It has been classified as critical. This affects an unknown function of the component Proxy Request Handler. The manipulation with an unknown input leads to a stack-based overflow vulnerability. CWE is classifying the issue as CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

libcoap versions up to and including 4.3.5, prior to commit 30db3ea, contain a stack-based buffer overflow in address resolution when attacker-controlled hostname data is copied into a fixed 256-byte stack buffer without proper bounds checking. A remote attacker can trigger a crash and potentially achieve remote code execution depending on compiler options and runtime memory protections. Exploitation requires the proxy logic to be enabled (i.e., the proxy request handling code path in an application using libcoap).

The weakness was disclosed by SecMate. The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2025-34468 since 04/15/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 281560 (Linux Distros Unpatched Vulnerability : CVE-2025-34468), which helps to determine the existence of the flaw in a target environment.

Applying the patch 30db3ea is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the databases at Tenable (281560) and EUVD (EUVD-2025-206064). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• libcoap

Version

• 4.3.0
• 4.3.1
• 4.3.2
• 4.3.3
• 4.3.4
• 4.3.5

License

• open-source

CPE 2.3info

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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