{"api_version":"1","generated_at":"2026-09-12T11:23:59+00:00","cve":"CVE-2026-89631","urls":{"html":"https://cve.report/CVE-2026-89631","api":"https://cve.report/api/cve/CVE-2026-89631.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89631","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89631"},"summary":{"title":"smb: client: reject a tree connect response whose byte count is too small","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: reject a tree connect response whose byte count is too small\n\nCIFSTCon() bounds its strnlen() over the byte area with the server's\nByteCount minus two, which for ByteCount 0 or 1 goes negative as an int\nand converts to a huge size_t.  The later subtraction wraps the __u16\nbytes_left, and that is what bounds cifs_strndup_from_utf16(): a bound of\nup to 65535 against a ~16 KB cifs_req_poolp object runs off the end of the\nslab object, and the bytes reach userspace through tcon->nativeFileSystem\nin /proc/fs/cifs/DebugData.\n\nReject a byte area too small for what the parser consumes.  Two bytes is\nthe least it can consume, and no conformant response carries fewer.  The\nnew trace point is the 129th smb_eio_trace entry, which __mode(byte)\ncannot represent, so the attribute goes with it.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:48","updated_at":"2026-09-11 20:19:48"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/65deb18359341141d37dc86fc7853511be3c87a7","name":"https://git.kernel.org/stable/c/65deb18359341141d37dc86fc7853511be3c87a7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/411e484fe71a7f1028de617447edad9cb6d9d68a","name":"https://git.kernel.org/stable/c/411e484fe71a7f1028de617447edad9cb6d9d68a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d","name":"https://git.kernel.org/stable/c/3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89631","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89631","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc20c031bb067eb3280a1c4b5c42295093e24863 3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc20c031bb067eb3280a1c4b5c42295093e24863 411e484fe71a7f1028de617447edad9cb6d9d68a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc20c031bb067eb3280a1c4b5c42295093e24863 65deb18359341141d37dc86fc7853511be3c87a7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.30","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.30 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.51 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/smb/client/cifssmb.c","fs/smb/client/trace.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d","status":"affected","version":"cc20c031bb067eb3280a1c4b5c42295093e24863","versionType":"git"},{"lessThan":"411e484fe71a7f1028de617447edad9cb6d9d68a","status":"affected","version":"cc20c031bb067eb3280a1c4b5c42295093e24863","versionType":"git"},{"lessThan":"65deb18359341141d37dc86fc7853511be3c87a7","status":"affected","version":"cc20c031bb067eb3280a1c4b5c42295093e24863","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/cifssmb.c","fs/smb/client/trace.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.30"},{"lessThan":"2.6.30","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.51","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":"6.18.51","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"2.6.30","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: reject a tree connect response whose byte count is too small\n\nCIFSTCon() bounds its strnlen() over the byte area with the server's\nByteCount minus two, which for ByteCount 0 or 1 goes negative as an int\nand converts to a huge size_t.  The later subtraction wraps the __u16\nbytes_left, and that is what bounds cifs_strndup_from_utf16(): a bound of\nup to 65535 against a ~16 KB cifs_req_poolp object runs off the end of the\nslab object, and the bytes reach userspace through tcon->nativeFileSystem\nin /proc/fs/cifs/DebugData.\n\nReject a byte area too small for what the parser consumes.  Two bytes is\nthe least it can consume, and no conformant response carries fewer.  The\nnew trace point is the 129th smb_eio_trace entry, which __mode(byte)\ncannot represent, so the attribute goes with it."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:45:26.444Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d"},{"url":"https://git.kernel.org/stable/c/411e484fe71a7f1028de617447edad9cb6d9d68a"},{"url":"https://git.kernel.org/stable/c/65deb18359341141d37dc86fc7853511be3c87a7"}],"title":"smb: client: reject a tree connect response whose byte count is too small","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89631","datePublished":"2026-09-11T19:45:26.444Z","dateReserved":"2026-09-11T19:38:34.738Z","dateUpdated":"2026-09-11T19:45:26.444Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:48","lastModifiedDate":"2026-09-11 20:19:48","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89631","Ordinal":"1","Title":"smb: client: reject a tree connect response whose byte count is ","CVE":"CVE-2026-89631","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89631","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: reject a tree connect response whose byte count is too small\n\nCIFSTCon() bounds its strnlen() over the byte area with the server's\nByteCount minus two, which for ByteCount 0 or 1 goes negative as an int\nand converts to a huge size_t.  The later subtraction wraps the __u16\nbytes_left, and that is what bounds cifs_strndup_from_utf16(): a bound of\nup to 65535 against a ~16 KB cifs_req_poolp object runs off the end of the\nslab object, and the bytes reach userspace through tcon->nativeFileSystem\nin /proc/fs/cifs/DebugData.\n\nReject a byte area too small for what the parser consumes.  Two bytes is\nthe least it can consume, and no conformant response carries fewer.  The\nnew trace point is the 129th smb_eio_trace entry, which __mode(byte)\ncannot represent, so the attribute goes with it.","Type":"Description","Title":"smb: client: reject a tree connect response whose byte count is "}]}}}