Memory disclosure or crash via unchecked CBOR reads
Published Apr 17, 2026 · Updated Apr 17, 2026
Out-of-bounds reads in libcoap before 4.3.5b allow remote attackers to expose memory or interrupt service through malformed OSCORE input. get_byte_inc() in src/oscore/oscore_cbor.c advances through Appendix B.2 CBOR input with only an assert() bounds check, which NDEBUG release builds remove. Reachability requires a libcoap client or server using OSCORE negotiation; crafted options or responses can read adjacent memory or crash the process.
Summary
What happened
Out-of-bounds reads in libcoap before 4.3.5b allow remote attackers to expose memory or interrupt service through malformed OSCORE input. get_byte_inc() in src/oscore/oscore_cbor.c advances through Appendix B.2 CBOR input with only an assert() bounds check, which NDEBUG release builds remove. Reachability requires a libcoap client or server using OSCORE negotiation; crafted options or responses can read adjacent memory or crash the process.
The record
- CVE
- CVE-2026-29013
- Published
- Apr 17, 2026
- Updated
- Apr 17, 2026
- Vendor
- libcoap
- Product
- libcoap
- Classifications
- CWE-125, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 17, 2026CVE publishedPublication date reported by the CVE source.
- Apr 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <v4.3.5b
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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