CVE-2025-34468 HIGH

CVE-2025-34468: libcoap Stack-Based Buffer Overflow in Address Resolution DoS or Potential RCE

Vendor Libcoap
Product libcoap
Weakness CWE-121
Published December 31, 2025
Last update March 23, 2026

CVSS base score

8.2/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

What the vulnerability does

01Description

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).

Key dates

02Disclosure timeline

December 31, 2025 CVE published
March 23, 2026 Record updated