{"id":"UBUNTU-CVE-2026-54522","details":"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.","modified":"2026-08-06T22:15:14.838907816Z","published":"2026-07-30T17:16:00Z","upstream":["CVE-2026-54522"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-54522"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-54522"},{"type":"REPORT","url":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938"}],"affected":[{"package":{"name":"ruby-msgpack","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/ruby-msgpack?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.6.2-1build1","0.6.2-1build2","0.6.2-1build3","0.6.2-1build4"],"ecosystem_specific":{"binaries":[{"binary_version":"0.6.2-1build4","binary_name":"ruby-msgpack"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54522.json"}},{"package":{"name":"ruby-msgpack","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/ruby-msgpack?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0-1","1.1.0-1","1.1.0-1build1","1.1.0-1build2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.1.0-1build2","binary_name":"ruby-msgpack"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54522.json"}},{"package":{"name":"ruby-msgpack","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/ruby-msgpack?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-1build2","1.1.0-1build3"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-msgpack","binary_version":"1.1.0-1build3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54522.json"}},{"package":{"name":"ruby-msgpack","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/ruby-msgpack?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-2build1","1.1.0-2build2","1.4.2-2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.4.2-2","binary_name":"ruby-msgpack"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54522.json"}},{"package":{"name":"ruby-msgpack","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/ruby-msgpack?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.2-2build2","1.4.2-2build3","1.4.2-2build4"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-msgpack","binary_version":"1.4.2-2build4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54522.json"}},{"package":{"name":"ruby-msgpack","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/ruby-msgpack?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.7.2-1.1","1.8.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-msgpack","binary_version":"1.8.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-54522.json"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V4","score":"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"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}