CVE-2026-29013 PUBLISHED

libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling

Assigner: VulnCheck
Reserved: 03.03.2026 Published: 17.04.2026 Updated: 20.04.2026

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 heap buffer overflow writes through integer wraparound in allocation size computation.

Metrics

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
CVSS Score: 8.8

Product Status

Vendor libcoap
Product libcoap
Versions Default: unknown
  • affected from 0 to v4.3.5b (excl.)

Credits

  • Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. finder

References

Problem Types

  • CWE-125: Out-of-bounds Read CWE