{"id":"CVE-2026-54522","state":"PUBLISHED","title":"MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure","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.","publishedAt":"2026-07-30T16:33:06.080Z","updatedAt":"2026-07-30T17:39:15.020Z","severity":{"score":2.1,"label":"Low","version":"4.0","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","source":"GitHub_M"},"assigner":"GitHub_M","products":["msgpack msgpack-ruby"],"affected":[{"vendor":"msgpack","product":"msgpack-ruby","versions":[{"version":"< 1.8.2","status":"affected"}]}],"references":["https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938","https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54522.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54522","state":"PUBLISHED","datePublished":"2026-07-30T16:33:06.080Z","dateUpdated":"2026-07-30T17:39:15.020Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-15T18:40:01.651Z"},"containers":{"cna":{"title":"MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"msgpack","product":"msgpack-ruby","versions":[{"version":"< 1.8.2","status":"affected"}]}],"references":[{"url":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938","name":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90","name":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":2.1,"baseSeverity":"LOW","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","description":"CWE-416: Use After Free","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-30T16:33:06.080Z"},"source":{"advisory":"GHSA-4mrv-5p47-p938","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-30T17:38:58.315032Z","id":"CVE-2026-54522","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-30T17:39:15.020Z"}}]}}}