Vulnerability · Published Dec 31, 2025 · Assigned by VulnCheck
CVE-2025-34468libcoap Stack-Based Buffer Overflow in Address Resolution DoS or Potential RCE
High 8.2
In plain English
A high-severity stack buffer overflow in libcoap from libcoap. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 55% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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).
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libcoap3 | no fix listed | DEBIAN-CVE-2025-34468 |
| Debian:13 | libcoap3 | 4.3.4-1.1+deb13u3 | DEBIAN-CVE-2025-34468 |
| Debian:14 | libcoap3 | 4.3.5-3 | DEBIAN-CVE-2025-34468 |
| Ubuntu:22.04:LTS | libcoap2 | no fix listed | UBUNTU-CVE-2025-34468 |
| Ubuntu:22.04:LTS | libcoap3 | no fix listed | UBUNTU-CVE-2025-34468 |
| Ubuntu:24.04:LTS | libcoap3 | no fix listed | UBUNTU-CVE-2025-34468 |
| Ubuntu:25.10 | libcoap3 | no fix listed | UBUNTU-CVE-2025-34468 |
| Ubuntu:26.04:LTS | libcoap3 | no fix listed | UBUNTU-CVE-2025-34468 |
| Ubuntu:26.10 | libcoap3 | no fix listed | UBUNTU-CVE-2025-34468 |
Affected products (as reported)
Weakness: CWE-121 · 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