{"api_version":"1","generated_at":"2026-09-12T11:23:59+00:00","cve":"CVE-2026-89651","urls":{"html":"https://cve.report/CVE-2026-89651","api":"https://cve.report/api/cve/CVE-2026-89651.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89651","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89651"},"summary":{"title":"ceph: bound MDSCapAuth path and fs_name decode in handle_session()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound MDSCapAuth path and fs_name decode in handle_session()\n\nhandle_session() decodes the MDSCapAuth records carried by a\nCEPH_SESSION_OPEN message (msg_version >= 6). For each record the\nmatch.path and match.fs_name byte strings are read by first decoding a\n32-bit length and then copying that many bytes with the bare\nceph_decode_copy(). Unlike the surrounding fields, which all use the\n_safe decode variants, these two copies are not preceded by a\nceph_decode_need() bounds check, and the enclosing MDSCapAuth and\nMDSCapMatch struct_len fields are skipped rather than enforced as an\nupper bound. A length larger than the bytes remaining in the message\nfront makes ceph_decode_copy() read past the end of the front buffer.\n\nThe message front is a dedicated allocation (ceph_msg_new2() ->\nkvmalloc), so the over-read runs off that object. A malicious or\ncompromised MDS can trigger this with the first post-connect message on\nmount, with no client-side user interaction; under KASAN it is reported\nas a slab-out-of-bounds read in handle_session().\n\nImpact: a malicious MDS can force the kernel client to read up to 4 GiB\npast the message front allocation during session setup, crashing the\nclient (out-of-bounds read).\n\nSwitch both copies to ceph_decode_copy_safe(), which performs the\nceph_decode_need() bounds check before the copy and branches to the\nexisting bad label, matching the rest of the decoder and the error path\nthat frees the partially decoded cap_auths array.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:51","updated_at":"2026-09-11 20:19:51"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/77933e22adfe813be2bd10be08d6e950103c3967","name":"https://git.kernel.org/stable/c/77933e22adfe813be2bd10be08d6e950103c3967","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c37db86d2b5e9b57001ccae7e7a727e95a4f9c02","name":"https://git.kernel.org/stable/c/c37db86d2b5e9b57001ccae7e7a727e95a4f9c02","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5f892c767b30e4fb0c744c59f9235c717383d2cd","name":"https://git.kernel.org/stable/c/5f892c767b30e4fb0c744c59f9235c717383d2cd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dc5c7dffda92ef372fa587c444a1c537373df824","name":"https://git.kernel.org/stable/c/dc5c7dffda92ef372fa587c444a1c537373df824","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89651","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89651","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1d17de9534cb5a4c4c380d174cc2f9281b34f89e dc5c7dffda92ef372fa587c444a1c537373df824 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1d17de9534cb5a4c4c380d174cc2f9281b34f89e c37db86d2b5e9b57001ccae7e7a727e95a4f9c02 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1d17de9534cb5a4c4c380d174cc2f9281b34f89e 5f892c767b30e4fb0c744c59f9235c717383d2cd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1d17de9534cb5a4c4c380d174cc2f9281b34f89e 77933e22adfe813be2bd10be08d6e950103c3967 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/ceph/mds_client.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"dc5c7dffda92ef372fa587c444a1c537373df824","status":"affected","version":"1d17de9534cb5a4c4c380d174cc2f9281b34f89e","versionType":"git"},{"lessThan":"c37db86d2b5e9b57001ccae7e7a727e95a4f9c02","status":"affected","version":"1d17de9534cb5a4c4c380d174cc2f9281b34f89e","versionType":"git"},{"lessThan":"5f892c767b30e4fb0c744c59f9235c717383d2cd","status":"affected","version":"1d17de9534cb5a4c4c380d174cc2f9281b34f89e","versionType":"git"},{"lessThan":"77933e22adfe813be2bd10be08d6e950103c3967","status":"affected","version":"1d17de9534cb5a4c4c380d174cc2f9281b34f89e","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/ceph/mds_client.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.10"},{"lessThan":"6.10","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.10","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound MDSCapAuth path and fs_name decode in handle_session()\n\nhandle_session() decodes the MDSCapAuth records carried by a\nCEPH_SESSION_OPEN message (msg_version >= 6). For each record the\nmatch.path and match.fs_name byte strings are read by first decoding a\n32-bit length and then copying that many bytes with the bare\nceph_decode_copy(). Unlike the surrounding fields, which all use the\n_safe decode variants, these two copies are not preceded by a\nceph_decode_need() bounds check, and the enclosing MDSCapAuth and\nMDSCapMatch struct_len fields are skipped rather than enforced as an\nupper bound. A length larger than the bytes remaining in the message\nfront makes ceph_decode_copy() read past the end of the front buffer.\n\nThe message front is a dedicated allocation (ceph_msg_new2() ->\nkvmalloc), so the over-read runs off that object. A malicious or\ncompromised MDS can trigger this with the first post-connect message on\nmount, with no client-side user interaction; under KASAN it is reported\nas a slab-out-of-bounds read in handle_session().\n\nImpact: a malicious MDS can force the kernel client to read up to 4 GiB\npast the message front allocation during session setup, crashing the\nclient (out-of-bounds read).\n\nSwitch both copies to ceph_decode_copy_safe(), which performs the\nceph_decode_need() bounds check before the copy and branches to the\nexisting bad label, matching the rest of the decoder and the error path\nthat frees the partially decoded cap_auths array."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:45:41.620Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/dc5c7dffda92ef372fa587c444a1c537373df824"},{"url":"https://git.kernel.org/stable/c/c37db86d2b5e9b57001ccae7e7a727e95a4f9c02"},{"url":"https://git.kernel.org/stable/c/5f892c767b30e4fb0c744c59f9235c717383d2cd"},{"url":"https://git.kernel.org/stable/c/77933e22adfe813be2bd10be08d6e950103c3967"}],"title":"ceph: bound MDSCapAuth path and fs_name decode in handle_session()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89651","datePublished":"2026-09-11T19:45:41.620Z","dateReserved":"2026-09-11T19:38:34.742Z","dateUpdated":"2026-09-11T19:45:41.620Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:51","lastModifiedDate":"2026-09-11 20:19:51","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89651","Ordinal":"1","Title":"ceph: bound MDSCapAuth path and fs_name decode in handle_session","CVE":"CVE-2026-89651","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89651","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound MDSCapAuth path and fs_name decode in handle_session()\n\nhandle_session() decodes the MDSCapAuth records carried by a\nCEPH_SESSION_OPEN message (msg_version >= 6). For each record the\nmatch.path and match.fs_name byte strings are read by first decoding a\n32-bit length and then copying that many bytes with the bare\nceph_decode_copy(). Unlike the surrounding fields, which all use the\n_safe decode variants, these two copies are not preceded by a\nceph_decode_need() bounds check, and the enclosing MDSCapAuth and\nMDSCapMatch struct_len fields are skipped rather than enforced as an\nupper bound. A length larger than the bytes remaining in the message\nfront makes ceph_decode_copy() read past the end of the front buffer.\n\nThe message front is a dedicated allocation (ceph_msg_new2() ->\nkvmalloc), so the over-read runs off that object. A malicious or\ncompromised MDS can trigger this with the first post-connect message on\nmount, with no client-side user interaction; under KASAN it is reported\nas a slab-out-of-bounds read in handle_session().\n\nImpact: a malicious MDS can force the kernel client to read up to 4 GiB\npast the message front allocation during session setup, crashing the\nclient (out-of-bounds read).\n\nSwitch both copies to ceph_decode_copy_safe(), which performs the\nceph_decode_need() bounds check before the copy and branches to the\nexisting bad label, matching the rest of the decoder and the error path\nthat frees the partially decoded cap_auths array.","Type":"Description","Title":"ceph: bound MDSCapAuth path and fs_name decode in handle_session"}]}}}