{"id":"CVE-2026-54522","summary":"MessagePack::Buffer#clear Use-After-Free that Enables Cross-Buffer Disclosure","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.","aliases":["GHSA-4mrv-5p47-p938"],"modified":"2026-08-12T16:41:18.513154Z","published":"2026-07-30T16:33:06.080Z","related":["CGA-3xmv-v2ph-r2x9"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-416"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54522.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54522.json"},{"type":"ADVISORY","url":"https://github.com/msgpack/msgpack-ruby/security/advisories/GHSA-4mrv-5p47-p938"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54522"},{"type":"FIX","url":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/msgpack/msgpack-ruby","events":[{"introduced":"0"},{"fixed":"09c914d75f296d6edb9fadb65b9ad614eb0bbfc7"},{"fixed":"5627d71606b565641d2dd501b82aae862f4abe90"}],"database_specific":{"source":["CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:msgpack:messagepack:*:*:*:*:*:ruby:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.8.2"}]}}],"versions":["v1.8.1","v1.8.0","v1.7.5","v1.7.4","v1.7.3","v1.7.2","v1.7.1","v1.7.0","v1.6.1","v1.6.0","v1.5.6","v1.5.5","v1.5.4","v1.5.3","v1.5.2","v1.5.1","v1.5.0","v1.4.5","v1.4.4","v1.4.3","v1.4.2","v1.4.1","v1.4.0","v1.3.3","v1.3.2","v1.3.1","v1.3.0","v1.2.10","v1.2.9","v1.2.8","v1.2.7","v1.2.6","v1.2.5","v1.2.4","v1.2.3","v1.2.2","v1.2.1","v1.2.0","v1.1.0","v1.0.3","v1.0.2","v1.0.1","v1.0.0","v0.7.6","v0.7.5","v0.7.4","v0.7.3","v0.7.2","v0.7.1","v0.7.0","v0.6.2","v0.6.1","v0.6.0","v0.6.0pre1","v0.5.11","v0.5.10","v0.5.9","v0.5.8","v0.5.7","v0.5.6","v0.5.5","v0.5.4","v0.5.3","v0.5.2","v0.5.1","v0.5.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54522.json","vanir_signatures_modified":"2026-08-12T16:41:18Z","vanir_signatures":[{"deprecated":false,"digest":{"threshold":0.9,"line_hashes":["62515399619151110189481082912345304106","157328647613235767233816264595413167422","82844948022617087820993061839250164793","82217288161328941814490663109635154035"]},"id":"CVE-2026-54522-0c48a748","signature_type":"Line","signature_version":"v1","source":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90","target":{"file":"ext/msgpack/buffer.c"}},{"deprecated":false,"digest":{"function_hash":"111911793690646822479415364421376939223","length":382},"id":"CVE-2026-54522-4de75f32","signature_type":"Function","signature_version":"v1","source":"https://github.com/msgpack/msgpack-ruby/commit/5627d71606b565641d2dd501b82aae862f4abe90","target":{"file":"ext/msgpack/buffer.c","function":"_msgpack_buffer_shift_chunk"}}]}}],"schema_version":"1.9.0","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"}]}