What’s Vulnerable › Vulnerabilities
CVE-2026-29013: libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling
- Severity: critical (CVSS 9.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-04-17 · updated 2026-06-17
- Weakness: CWE-125
Description
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.
Affected products
- libcoap: before 4.3.5b — fixed in 4.3.5b
How to fix
Upgrade to a fixed version: libcoap 4.3.5b. Check the vendor advisory for mitigations.
References
Get alerted when CVE-2026-29013 or the next vulnerability affects your stack