CVE catalog

CVE-2025-34468

libcoap3: CVE-2025-34468

Severity: Critical · CVSS 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: Dec 31, 2025, 6:39:07 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.75% · Oct 25, 2026

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).

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	libcoap3	sid	`4.3.5-4`	fixed
Debian	libcoap3	forky	`4.3.5-4`	fixed
Debian	libcoap3	trixie	`4.3.4-1.1+deb13u3`	fixed
Debian	libcoap3	bookworm	`4.3.1-1`	vulnerable
Cpe	libcoap	Not reported	Not reported	unknown

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	libcoap3	source	sid	`4.3.5-3`	not yet assigned	Not reported	[1124407]
Debian	libcoap3	source	forky	`4.3.5-3`	not yet assigned	Not reported	[1124407]
Debian	libcoap3	source	trixie	`4.3.4-1.1+deb13u3`	not yet assigned	Not reported	[1124407]
Debian	libcoap3	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1124407]

[Debian bug #1124407]

Notes

[bookworm] libcoap3: Minor issue

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libcoap3]Affected
Details (2)
- 4.3.1-1 · amd64 · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
- 4.3.1-1 · arm64 · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
[libcoap3-bin]Affected
Source package: [libcoap3]
Details (2)
- 4.3.1-1 · amd64 · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
- 4.3.1-1 · arm64 · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
[libcoap3-dev]Affected
Source package: [libcoap3]
Details (2)
- 4.3.1-1 · amd64 · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
- 4.3.1-1 · arm64 · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
[libcoap3-doc]Affected
Source package: [libcoap3]
Details (2)
- 4.3.1-1 · all · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12
- 4.3.1-1 · all · bookworm
  Affected
  dsa · libcoap3 · debian · bookworm; dsa · libcoap3 · debian · 12

[Debian 13 (Trixie)]

[libcoap3-bin]Fixed
Source package: [libcoap3]
Details (2)
- 4.3.4-1.1+deb13u3 · amd64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · arm64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
[libcoap3-dev]Fixed
Source package: [libcoap3]
Details (2)
- 4.3.4-1.1+deb13u3 · amd64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · arm64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
[libcoap3-doc]Fixed
Source package: [libcoap3]
Details (2)
- 4.3.4-1.1+deb13u3 · all · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · all · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
[libcoap3t64]Fixed
Source package: [libcoap3]
Details (2)
- 4.3.4-1.1+deb13u3 · amd64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · arm64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u3
  dsa · libcoap3 · debian · 13

Observed: Oct 24, 2026, 7:43:53 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]