{"schema":"threatline.record/2","record":{"id":"CVE-2026-97559","aliases":[],"summary":"smb: client: fail DACL rewrite when the new DACL exceeds 64K","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fail DACL rewrite when the new DACL exceeds 64K\n\nreplace_sids_and_copy_aces() and set_chmod_dacl() accumulate the size of\nthe DACL they build in a u16. That accumulator can wrap.\n\nvalidate_dacl() caps num_aces at (dacl_size - sizeof(struct smb_acl)) /\n20, i.e. 3276 for a maximally sized DACL, while each rewritten ACE can\ngrow to sizeof(struct smb_ace) (76 bytes) once its SID is replaced with\none carrying SID_MAX_SUB_AUTHORITIES sub-authorities. The worst case is\ntherefore sizeof(struct smb_acl) + 3276 * 76 = 248984 bytes, far beyond\nwhat a u16 can hold. A wraparound is reached with 863 ACEs.\n\nAfter the wraparound, ndacl_ptr->size becomes meaningless and the offset\nwill point anywhere in the ACE array. As a result, we will see\ncorruption of the DACL, which then gets sent to the server. This is not\nan out-of-bounds write as the allocation now covers the worst-case\nexpansion, so writes will always go into the buffer.\n\nAdjust the code to use a u32 internally and return -EOVERFLOW in the\noverflow case. The operation must be refused, because a DACL can only\nhold 2^16-1 bytes on the wire and larger DACLs cannot be represented.\n\nset_chmod_dacl() carries the same pattern and is fixed the same way. It\nonly wraps once the source DACL comes within roughly 380 bytes of the\n64K ceiling, but the failure mode is identical.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97559","source_modified_at":"2026-10-21T12:53:17.080Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"f5065508897a922327f32223082325d10b069ebc","lessThan":"284877c6189fda1ac3d81771dd8482660a0c7dc1","status":"affected","versionType":"git"},{"version":"f5065508897a922327f32223082325d10b069ebc","lessThan":"d433376abc47e10870ae732f89c7c1a60b199a0c","status":"affected","versionType":"git"},{"version":"f5065508897a922327f32223082325d10b069ebc","lessThan":"2ef532a01f44687f5b95001e88247cf05bff9892","status":"affected","versionType":"git"},{"version":"f5065508897a922327f32223082325d10b069ebc","lessThan":"ee13d687d06a6fbb2008625dd560c654231b28e0","status":"affected","versionType":"git"},{"version":"f5065508897a922327f32223082325d10b069ebc","lessThan":"d05045177a855386bca5e1909e08d06290e6e3b3","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97559","source_modified_at":"2026-10-21T12:53:17.080Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"5.12","status":"affected"},{"version":"0","lessThan":"5.12","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.112","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97559","source_modified_at":"2026-10-21T12:53:17.080Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"284877c6189fda1ac3d81771dd8482660a0c7dc1","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97559","source_modified_at":"2026-10-21T12:53:17.080Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"2ef532a01f44687f5b95001e88247cf05bff9892","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.002,"percentile":0.09303,"score_date":"2026-10-23"},"published_at":"2026-09-25T10:21:48.866Z","modified_at":"2026-10-21T12:53:17.080Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-97559","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-21T12:53:17.080Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-97559","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/284877c6189fda1ac3d81771dd8482660a0c7dc1"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/d433376abc47e10870ae732f89c7c1a60b199a0c"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/2ef532a01f44687f5b95001e88247cf05bff9892"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/ee13d687d06a6fbb2008625dd560c654231b28e0"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/d05045177a855386bca5e1909e08d06290e6e3b3"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-21T12:53:17.080Z","content_hash":"401d9239a0d8d9a3ce7ad91f9b9afeabf7f99f2302966598b28597e8f93116d3"}}