Out-of-bounds Write Affecting libcoap3 package, versions <4.3.5-3


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.75% (54th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-LIBCOAP3-14806532
  • published1 Jan 2026
  • disclosed31 Dec 2025

Introduced: 31 Dec 2025

CVE-2025-34468  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Debian:unstable libcoap3 to version 4.3.5-3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libcoap3 package and not the libcoap3 package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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).

CVSS Base Scores

version 3.1