CVE-2026-29013
libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling
Reported by vulncheck · Published April 17, 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 out-of-bounds reads through integer wraparound in allocation size computation.
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| libcoap | libcoap | 0 |
| libcoap | libcoap | 0 |
Timeline
- Apr 17, 2026 CVE Published
- Apr 17, 2026 CVE Updated
- Apr 17, 2026 PoC Published
- Apr 20, 2026 Security Advisory
- May 18, 2026 EPSS Score (30 in total, the first dated here)
- Jul 7, 2026 Coalition ESS Score
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References
- patch
- https://www.vulncheck.com/advisories/libcoap-out-of-bounds-read-in-oscore-cbor-unwrap-handling third-party-advisory