Out-of-Bounds Read in OSCORE Appendix B.2 CBOR unwrap handling (CVE-2026-29013)
Summary
Vulnerability in OSCORE Appendix B.2 CBOR unwrap handling (CVE-2026-29013). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-29013 has been found in OSCORE Appendix B.2 CBOR unwrap handling.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "OSCORE Appendix B.2 CBOR unwrap handling CVE-2026-29013" on the vendor's site.
CVE-2026-29013 (OSCORE Appendix B.2 CBOR unwrap handling) — CWE-125 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds read (CWE-125) exists in OSCORE Appendix B.2 CBOR unwrap handling.
Check the vendor advisory for the affected versions of OSCORE Appendix B.2 CBOR unwrap handling.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで OSCORE Appendix B.2 CBOR unwrap handling を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-29013 libcoap3
- Ubuntu UBUNTU-CVE-2026-29013 libcoap
References
- advisory nvd.nist.gov
- advisory github.com
- patch github.com
- web vulncheck.com
- web github.com