{"api_version":"1","generated_at":"2026-09-12T18:14:19+00:00","cve":"CVE-2026-89633","urls":{"html":"https://cve.report/CVE-2026-89633","api":"https://cve.report/api/cve/CVE-2026-89633.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89633","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89633"},"summary":{"title":"smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()\n\ncoalesce_t2() computes data pointers directly from server-supplied\nDataOffset fields with no validation against buffer bounds:\n\n  data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +\n                     get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);\n  data_area_of_src = (char *)&pSMBs->hdr.Protocol +\n                     get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);\n  data_area_of_tgt += total_in_tgt;\n  ...\n  memcpy(data_area_of_tgt, data_area_of_src, total_in_src);\n\nA small DataOffset can push a pointer below the actual byte area,\noverwriting header fields; a large one can push it past the buffer\nend, causing out-of-bounds heap reads (source) or writes (target).\nThe BCC overflow guard does not prevent this: BCC reflects how much\ndata is present, while DataOffset controls where in the buffer it\nstarts.\n\nThe \"validate target area\" comment present since the function was\nfirst written in 2005 was a placeholder that was never implemented.\n\nAdd lower- and upper-bound checks for both data pointers before the\nmemcpy, and before any target header fields are modified.","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/033bc80019f07d158630df4e69b19a49010f54f1","name":"https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e","name":"https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b","name":"https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89633","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89633","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e4eb295d38b57f4d4b956942a48887eb252d97c6 672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e4eb295d38b57f4d4b956942a48887eb252d97c6 033bc80019f07d158630df4e69b19a49010f54f1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e4eb295d38b57f4d4b956942a48887eb252d97c6 6343c1da561962688f203362d80d6a3bfa39fa1b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.12","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.12 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/smb1transport.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e","status":"affected","version":"e4eb295d38b57f4d4b956942a48887eb252d97c6","versionType":"git"},{"lessThan":"033bc80019f07d158630df4e69b19a49010f54f1","status":"affected","version":"e4eb295d38b57f4d4b956942a48887eb252d97c6","versionType":"git"},{"lessThan":"6343c1da561962688f203362d80d6a3bfa39fa1b","status":"affected","version":"e4eb295d38b57f4d4b956942a48887eb252d97c6","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/smb1transport.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.12"},{"lessThan":"2.6.12","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":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"2.6.12","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()\n\ncoalesce_t2() computes data pointers directly from server-supplied\nDataOffset fields with no validation against buffer bounds:\n\n  data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +\n                     get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);\n  data_area_of_src = (char *)&pSMBs->hdr.Protocol +\n                     get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);\n  data_area_of_tgt += total_in_tgt;\n  ...\n  memcpy(data_area_of_tgt, data_area_of_src, total_in_src);\n\nA small DataOffset can push a pointer below the actual byte area,\noverwriting header fields; a large one can push it past the buffer\nend, causing out-of-bounds heap reads (source) or writes (target).\nThe BCC overflow guard does not prevent this: BCC reflects how much\ndata is present, while DataOffset controls where in the buffer it\nstarts.\n\nThe \"validate target area\" comment present since the function was\nfirst written in 2005 was a placeholder that was never implemented.\n\nAdd lower- and upper-bound checks for both data pointers before the\nmemcpy, and before any target header fields are modified."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:45:28.083Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e"},{"url":"https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1"},{"url":"https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b"}],"title":"smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89633","datePublished":"2026-09-11T19:45:28.083Z","dateReserved":"2026-09-11T19:38:34.739Z","dateUpdated":"2026-09-11T19:45:28.083Z","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":"89633","Ordinal":"1","Title":"smb: client: fix OOB read/write from unvalidated DataOffset in c","CVE":"CVE-2026-89633","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89633","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()\n\ncoalesce_t2() computes data pointers directly from server-supplied\nDataOffset fields with no validation against buffer bounds:\n\n  data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +\n                     get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);\n  data_area_of_src = (char *)&pSMBs->hdr.Protocol +\n                     get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);\n  data_area_of_tgt += total_in_tgt;\n  ...\n  memcpy(data_area_of_tgt, data_area_of_src, total_in_src);\n\nA small DataOffset can push a pointer below the actual byte area,\noverwriting header fields; a large one can push it past the buffer\nend, causing out-of-bounds heap reads (source) or writes (target).\nThe BCC overflow guard does not prevent this: BCC reflects how much\ndata is present, while DataOffset controls where in the buffer it\nstarts.\n\nThe \"validate target area\" comment present since the function was\nfirst written in 2005 was a placeholder that was never implemented.\n\nAdd lower- and upper-bound checks for both data pointers before the\nmemcpy, and before any target header fields are modified.","Type":"Description","Title":"smb: client: fix OOB read/write from unvalidated DataOffset in c"}]}}}