[Debian-iot-maintainers] Bug#1134340: libcoap3: CVE-2026-29013

[Salvatore Bonaccorso]

Source: libcoap3
Version: 4.3.5-2
Severity: important
Tags: security upstream
X-Debbugs-Cc: carnil at debian.org, Debian Security Team <team at security.debian.org>

Hi,

The following vulnerability was published for libcoap3.

CVE-2026-29013[0]:
| 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 heap buffer
| overflow writes through integer wraparound in allocation size
| computation.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-29013
    https://www.cve.org/CVERecord?id=CVE-2026-29013
[1] https://github.com/obgm/libcoap/commit/b7847c4dbb0dbee7c90b09a673d4cae256f03718

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore