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VulnerabilityPublished Updated

CVE-2024-31031: Libcoap2 · An issue in coap_pdu.c in libcoap 4.3.4 allows attackers to cause undefined behavior via a

Affects libcoap2Source GCVE Database

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Authoritative record:CVE-2024-31031· High 7.5

Not known to be exploited · CVSS 7.5 High.

Data as of 9 Nov 2026, 14:35 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 17 Apr 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10libcoap3pkg:deb/ubuntu/libcoap3?arch=source&distro=stonkingOther threatsAffected
  • 4.3.5-2 – 4.3.5-4ubuntu1
4 affected builds
Fixed in–
Ubuntu 26.04 LTSlibcoap3pkg:deb/ubuntu/libcoap3?arch=source&distro=resoluteOther threatsAffected
  • =4.3.4-1.1build4
  • =4.3.5-1
  • =4.3.5-2
Fixed in–
Ubuntu 25.10libcoap3pkg:deb/ubuntu/libcoap3?arch=source&distro=questingOther threatsAffected
  • =4.3.4-1.1build4
Fixed in–
Ubuntu 24.04 LTSlibcoap3pkg:deb/ubuntu/libcoap3?arch=source&distro=nobleOther threatsAffected
  • 4.3.1-2 – 4.3.4-1.1build4
6 affected builds
Fixed in–
Ubuntu 22.04 LTSlibcoap2pkg:deb/ubuntu/libcoap2?arch=source&distro=jammyOther threatsAffected
  • =4.2.1-1
  • =4.2.1-1build1
Fixed in–
Ubuntu 22.04 LTSlibcoap3pkg:deb/ubuntu/libcoap3?arch=source&distro=jammyOther threatsAffected
  • =4.3.0-2
  • =4.3.0-2build1
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, consider limiting exposure of affected libcoap2 services to untrusted networks.

Description

A vulnerability in libcoap 4.3.4's coap_pdu.c allows attackers to trigger undefined behavior through a sequence of messages causing an unsigned integer overflow. This flaw can result in a denial of service due to application crash or instability. The issue affects multiple specific versions of libcoap2 and has a high severity rating with a CVSS score of 7.5.

References

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