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.
Published: 2026-07-30
Score: 2.1 Low
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-4mrv-5p47-p938 MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure
History

Thu, 30 Jul 2026 20:15:00 +0000

Type Values Removed Values Added
First Time appeared Msgpack
Msgpack msgpack
Vendors & Products Msgpack
Msgpack msgpack

Thu, 30 Jul 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 30 Jul 2026 17:00:00 +0000

Type Values Removed Values Added
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.
Title MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure
Weaknesses CWE-416
References
Metrics cvssV4_0

{'score': 2.1, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-30T17:39:15.020Z

Reserved: 2026-06-15T18:40:01.651Z

Link: CVE-2026-54522

cve-icon Vulnrichment

Updated: 2026-07-30T17:38:06.996Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-30T20:00:18Z

Weaknesses