CVE-2026-29013 HIGH

CVE-2026-29013: libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling

Vendor Libcoap
Product libcoap
Weakness CWE-125
Published April 17, 2026
Last update May 25, 2026

CVSS base score

8.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N

What the vulnerability does

01Description

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers can send crafted CoAP requests with malformed OSCORE options or responses during OSCORE negotiation to trigger out-of-bounds reads during CBOR parsing and potentially cause out-of-bounds reads through integer wraparound in allocation size computation.

Key dates

02Disclosure timeline

April 17, 2026 CVE published
May 25, 2026 Record updated