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TI-2026-23178 Aliases CVE-2026-29013GHSA-4vrr-6f8v-98rf

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

Priority MEDIUM 44CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · Low · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00296 22nd percentileScored 2026-11-07
Fix Fixed libcoap (libcoap): v4.3.5b

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
libcoaplibcoapbefore v4.3.5bv4.3.5bPatch availableCNA
  • libcoap Vendorlibcoap Affected before v4.3.5b Fixed in v4.3.5b Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:libcoap:libcoap:*:*:*:*:*:*:*:*before 4.3.5bVulnerablelibcoap
  • cpe:2.3:a:libcoap:libcoap:*:*:*:*:*:*:*:* Versions before 4.3.5b Vulnerable ·libcoap

Remediation

  • Fix · CNA libcoap (libcoap) Fixed in v4.3.5b

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-29013
  2. 2026-10-03 Alias added: GHSA-4vrr-6f8v-98rf

References

Patch 1

  • TI-2024-00887 obgm libcoap Configuration File coap_oscore.c get_split_entry stack-based overflow CVSS 3.1HIGH 7.8
  • TI-2024-20447 An issue in `coap_pdu.c` in libcoap 4.3.4 allows attackers to cause undefined behavior… CVSS 3.1HIGH 7.5
  • TI-2023-17937 libcoap 4.3.1 contains a buffer over-read via the function coap_parse_oscore_conf_mem at coap_oscore.c. CVSS 3.1MEDIUM 6.5
  • TI-2023-14242 Buffer Overflow vulnerability in coap_send function in libcoap library 4.3.1-103-g52cfd56… CVSS 3.1HIGH 7.5
  • TI-2025-40369 NULL pointer dereference in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote… CVSS 3.1HIGH 7.5
  • TI-2025-40371 Integer signedness error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap… CVSS 3.1HIGH 7.5
See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences