CVE catalog

CVE-2025-65496

libcoap3: CVE-2025-65496

Severity: High · CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: Nov 24, 2025, 12:00:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.28% · Oct 25, 2026

NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS handshake that triggers SSL_get_SSL_CTX() to return NULL.

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

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	libcoap3	source	sid	`4.3.5-2`	not yet assigned	Not reported	[1121415]
Debian	libcoap3	source	forky	`4.3.5-2`	not yet assigned	Not reported	[1121415]
Debian	libcoap3	source	trixie	`4.3.4-1.1+deb13u2`	not yet assigned	Not reported	[1121415]
Debian	libcoap3	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1121415]

[Debian bug #1121415]

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+deb13u2
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · arm64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u2
  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+deb13u2
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · arm64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u2
  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+deb13u2
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · all · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u2
  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+deb13u2
  dsa · libcoap3 · debian · 13
- 4.3.4-1.1+deb13u3 · arm64 · trixie
  Fixed · Fixed: 4.3.4-1.1+deb13u2
  dsa · libcoap3 · debian · 13

Observed: Oct 24, 2026, 8:33:51 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]