CVE-2026-72854— msgpack-c 整数溢出导致分配过小
一分钟漏洞结论
影响对象
msgpack msgpack-c
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
src/unpack.c 中的 函数，通过公共 API 被调用。该函数使用未检查溢出的 加法来计算新缓冲区的大小，即把请求的大小与已使用的量相加。虽然其“翻倍”循环对自身乘法操作的溢出进行了防护，但循环条件中的加法缺乏防护。当请求的大小接近 时，加法会发生回绕（wrap around），导致循环条件在计算前就已满足；此时实际分配的缓冲区大小仅为回绕前的较小值，但函数仍返回真（true）。 因此，调用者被错误地告知已为其请求的容量预留了空间，而实际上并未预留。随后，若以请求的长度向该缓冲区写入数据，将导致堆缓冲区溢出
可能的 ATT&CK 技术 1 AI
T1190 · Exploit Public-Facing Application
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一、 漏洞 CVE-2026-72854 基础信息
漏洞信息
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Vulnerability Title
msgpack-c Integer Overflow in msgpack_unpacker_expand_buffer Causes a False-Success Undersized Reservation
来源: CVE Program / CVE List V5
Vulnerability Description
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.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:L
来源: CVE Program / CVE List V5
Vulnerability Type
整数溢出或超界折返
来源: CVE Program / CVE List V5
受影响产品
二、漏洞 CVE-2026-72854 的公开POC
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CVE-2026-72854 补丁与修复 (1)
CVE-2026-72854 厂商安全公告 (2)
CVE-2026-72854 厂商页面 (1)
CVE-2026-72854 其他参考 (1)
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🔗 msgpack-c/include/msgpack/unpack.h at c-7.0.1 · msgpack/msgpack-c · GitHub technical-description
IV. Related Vulnerabilities
V. Comments for CVE-2026-72854
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