DEBIAN-CVE-2026-72854
- Source
- https://security-tracker.debian.org/tracker/CVE-2026-72854
- Import Source
- https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-72854.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-72854
- Upstream
- Published
- 2026-08-20T19:17:01Z
- Modified
- 2026-09-01T16:07:00Z
- Severity
-
- 5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:L CVSS Calculator
- Summary
- [none]
- Details
-
msgpack_unpacker_expand_buffer in src/unpack.c, reached through the public msgpack_unpacker_reserve_buffer API, computes its new buffer size using an unchecked size_t addition of the requested size and the amount already used. The doubling loop guards its own multiplication against overflow, but the addition in the loop condition is unguarded, so a request near SIZE_MAX wraps: the loop condition is already satisfied, the allocation is performed at the small pre-wrap size, and the function returns true. The caller is told the requested capacity was reserved when it was not, so a subsequent write of the requested length overflows the heap buffer. The library's own example/lib_buffer_unpack.c demonstrates the reserve-then-write pattern, and its defensive assert comparing capacity against the request is compiled out under NDEBUG. msgpack-c's own decode entry points do not derive the reservation size from untrusted input, so reaching this requires an integration that passes an attacker-influenced length to the reservation API, such as a length-prefixed streaming transport.
- References
Affected packages
Debian:12 / msgpack-c
Package
- Name
- msgpack-c
- Purl
- pkg:deb/debian/msgpack-c?arch=source&distro=bookworm
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affected
Debian:13 / msgpack-c
Package
- Name
- msgpack-c
- Purl
- pkg:deb/debian/msgpack-c?arch=source&distro=trixie
Debian:14 / msgpack-c
Package
- Name
- msgpack-c
- Purl
- pkg:deb/debian/msgpack-c?arch=source&distro=forky