{"api_version":"1","generated_at":"2026-07-28T08:01:07+00:00","cve":"CVE-2026-64400","urls":{"html":"https://cve.report/CVE-2026-64400","api":"https://cve.report/api/cve/CVE-2026-64400.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64400","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64400"},"summary":{"title":"ksmbd: prevent path traversal bypass by restricting caseless retry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: prevent path traversal bypass by restricting caseless retry\n\nksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path\nresolution within the share root. When a crafted path attempts to\nescape the share boundary using parent-directory components ('..'),\nvfs_path_parent_lookup() detects this and immediately fails,\nreturning -EXDEV.\n\nHowever, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.\nThe function fails to intercept the -EXDEV error and erroneously\nfalls through to the caseless retry logic, which is intended only\nfor genuinely missing files. During this retry process, the path\nis reconstructed, leading to an unintended LOOKUP_BENEATH bypass\nthat allows write-capable users to create zero-length files or\ndirectories outside the exported share.\n\nFix this by ensuring that the execution only proceeds to the caseless\nlookup retry when the error is specifically -ENOENT. Any other errors,\nsuch as -EXDEV from a path traversal attempt, must be returned immediately.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:23","updated_at":"2026-07-27 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64400","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 74d7970febf7e9005375aeda0df821d2edffc9f7 8c9a4f1327eb71efbf14842e7b8a6d965077eb67 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 74d7970febf7e9005375aeda0df821d2edffc9f7 54bab9ba5a9f156ffa9324fcbe5a356fd0242f95 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 019aae488dbc67c97a33db03652e20e2c9e3afa7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6927ffe7479c72e7ebf885507227266a75f7c97d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ef6cc1c465786b3e4e735d1ab8b616b3e94402df 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the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: prevent path traversal bypass by restricting caseless retry\n\nksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path\nresolution within the share root. When a crafted path attempts to\nescape the share boundary using parent-directory components ('..'),\nvfs_path_parent_lookup() detects this and immediately fails,\nreturning -EXDEV.\n\nHowever, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.\nThe function fails to intercept the -EXDEV error and erroneously\nfalls through to the caseless retry logic, which is intended only\nfor genuinely missing files. During this retry process, the path\nis reconstructed, leading to an unintended LOOKUP_BENEATH bypass\nthat allows write-capable users to create zero-length files or\ndirectories outside the exported share.\n\nFix this by ensuring that the execution only proceeds to the caseless\nlookup retry when the error is specifically -ENOENT. Any other errors,\nsuch as -EXDEV from a path traversal attempt, must be returned immediately."}],"metrics":[{"cvssV3_1":{"baseScore":8.6,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-07-27T05:00:31.935Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/8c9a4f1327eb71efbf14842e7b8a6d965077eb67"},{"url":"https://git.kernel.org/stable/c/54bab9ba5a9f156ffa9324fcbe5a356fd0242f95"}],"title":"ksmbd: prevent path traversal bypass by restricting caseless retry","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64400","datePublished":"2026-07-25T08:50:43.655Z","dateReserved":"2026-07-19T15:36:31.785Z","dateUpdated":"2026-07-27T05:00:31.935Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:23","lastModifiedDate":"2026-07-27 05:16:47","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","baseScore":8.6,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":4.7}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64400","Ordinal":"1","Title":"ksmbd: prevent path traversal bypass by restricting caseless ret","CVE":"CVE-2026-64400","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64400","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: prevent path traversal bypass by restricting caseless retry\n\nksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path\nresolution within the share root. When a crafted path attempts to\nescape the share boundary using parent-directory components ('..'),\nvfs_path_parent_lookup() detects this and immediately fails,\nreturning -EXDEV.\n\nHowever, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.\nThe function fails to intercept the -EXDEV error and erroneously\nfalls through to the caseless retry logic, which is intended only\nfor genuinely missing files. During this retry process, the path\nis reconstructed, leading to an unintended LOOKUP_BENEATH bypass\nthat allows write-capable users to create zero-length files or\ndirectories outside the exported share.\n\nFix this by ensuring that the execution only proceeds to the caseless\nlookup retry when the error is specifically -ENOENT. Any other errors,\nsuch as -EXDEV from a path traversal attempt, must be returned immediately.","Type":"Description","Title":"ksmbd: prevent path traversal bypass by restricting caseless ret"}]}}}