Microsoft security update for CVE-2026-72854 — azl3
🔗 CVE IDs covered (1)
📋 Microsoft's advisory
EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72854. This page also shows what EchelonGraph holds for CVE-2026-72854, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.
🎯 Affected products6
- azl3 fluent-bit 3.1.10-6 on Azure Linux 3.0
- azl3 fluent-bit 3.1.10-7 on Azure Linux 3.0
- azl3 fluent-bit 3.1.10-8 on Azure Linux 3.0
- azl3 fluent-bit 3.1.10-9 on Azure Linux 3.0
- azl3 lttng-tools 2.13.11-1 on Azure Linux 3.0
- azl3 msgpack 3.3.0-1 on Azure Linux 3.0
✅ Updates Microsoft lists: 1 update
1 row: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.
| KB article | Update | Fixed build |
|---|---|---|
| — | Security Update | — |
🧭 EchelonGraph on CVE-2026-72854
- EchelonGraph score
- 5.3 MEDIUM
- CISA KEV
- Not listed
- Fix status
- A fix is available — apply it.
Description from the CVE record (CVE.org), as published by its numbering authority
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.
Published by VulnCheck, the CVE Numbering Authority that assigned CVE-2026-72854, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).