CVE-2026-54522 – MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure

CVE ID :CVE-2026-54522

Published : July 30, 2026, 5:16 p.m. | 28 minutes ago

Description :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.

Severity: 2.1 | LOW

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