CVE-2026-54522
LOWMessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure
Title source: cnaDescription
MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Buffer#clear in ext/msgpack/buffer.c leaves rmem_last, rmem_end, and rmem_owner stale after _msgpack_buffer_shift_chunk returns an rmem page to the shared pool, allowing a subsequent Buffer#write and a second MessagePack::Buffer to alias the page and disclose or corrupt cross-buffer data. This issue is fixed in version 1.8.2.
References (2)
Core 2
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938
X_Refsource_Misc x_refsource_misc
https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90
Scores
CVSS v4
2.1
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-416
Status
published
Products (2)
msgpack/msgpack-ruby
< 1.8.2
rubygems/msgpack
0 - 1.8.2RubyGems
Published
Jul 30, 2026
Tracked Since
Jul 30, 2026