{"api_version":"1","generated_at":"2026-04-25T14:02:26+00:00","cve":"CVE-2026-31613","urls":{"html":"https://cve.report/CVE-2026-31613","api":"https://cve.report/api/cve/CVE-2026-31613.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31613","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31613"},"summary":{"title":"smb: client: fix OOB reads parsing symlink error response","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB reads parsing symlink error response\n\nWhen a CREATE returns STATUS_STOPPED_ON_SYMLINK, smb2_check_message()\nreturns success without any length validation, leaving the symlink\nparsers as the only defense against an untrusted server.\n\nsymlink_data() walks SMB 3.1.1 error contexts with the loop test \"p <\nend\", but reads p->ErrorId at offset 4 and p->ErrorDataLength at offset\n0.  When the server-controlled ErrorDataLength advances p to within 1-7\nbytes of end, the next iteration will read past it.  When the matching\ncontext is found, sym->SymLinkErrorTag is read at offset 4 from\np->ErrorContextData with no check that the symlink header itself fits.\n\nsmb2_parse_symlink_response() then bounds-checks the substitute name\nusing SMB2_SYMLINK_STRUCT_SIZE as the offset of PathBuffer from\niov_base.  That value is computed as sizeof(smb2_err_rsp) +\nsizeof(smb2_symlink_err_rsp), which is correct only when\nErrorContextCount == 0.\n\nWith at least one error context the symlink data sits 8 bytes deeper,\nand each skipped non-matching context shifts it further by 8 +\nALIGN(ErrorDataLength, 8).  The check is too short, allowing the\nsubstitute name read to run past iov_len.  The out-of-bound heap bytes\nare UTF-16-decoded into the symlink target and returned to userspace via\nreadlink(2).\n\nFix this all up by making the loops test require the full context header\nto fit, rejecting sym if its header runs past end, and bound the\nsubstitute name against the actual position of sym->PathBuffer rather\nthan a fixed offset.\n\nBecause sub_offs and sub_len are 16bits, the pointer math will not\noverflow here with the new greater-than.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-04-24 15:16:40","updated_at":"2026-04-24 17:51:40"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/e0dd90d14cbbf318157ea8e3fb62ee68a28655ed","name":"https://git.kernel.org/stable/c/e0dd90d14cbbf318157ea8e3fb62ee68a28655ed","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a66ef2e7ed837325c5600f8617d5ee0a0a149fdd","name":"https://git.kernel.org/stable/c/a66ef2e7ed837325c5600f8617d5ee0a0a149fdd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/781902e069f4ecb6c3b83502f181972c1446110a","name":"https://git.kernel.org/stable/c/781902e069f4ecb6c3b83502f181972c1446110a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31613","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31613","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 e0dd90d14cbbf318157ea8e3fb62ee68a28655ed git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 781902e069f4ecb6c3b83502f181972c1446110a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 a66ef2e7ed837325c5600f8617d5ee0a0a149fdd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.24 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.14 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.1 7.0.* semver","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/smb2file.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"e0dd90d14cbbf318157ea8e3fb62ee68a28655ed","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"781902e069f4ecb6c3b83502f181972c1446110a","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"a66ef2e7ed837325c5600f8617d5ee0a0a149fdd","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/smb2file.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.24","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.14","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.1","versionType":"semver"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.24","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.1","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 reads parsing symlink error response\n\nWhen a CREATE returns STATUS_STOPPED_ON_SYMLINK, smb2_check_message()\nreturns success without any length validation, leaving the symlink\nparsers as the only defense against an untrusted server.\n\nsymlink_data() walks SMB 3.1.1 error contexts with the loop test \"p <\nend\", but reads p->ErrorId at offset 4 and p->ErrorDataLength at offset\n0.  When the server-controlled ErrorDataLength advances p to within 1-7\nbytes of end, the next iteration will read past it.  When the matching\ncontext is found, sym->SymLinkErrorTag is read at offset 4 from\np->ErrorContextData with no check that the symlink header itself fits.\n\nsmb2_parse_symlink_response() then bounds-checks the substitute name\nusing SMB2_SYMLINK_STRUCT_SIZE as the offset of PathBuffer from\niov_base.  That value is computed as sizeof(smb2_err_rsp) +\nsizeof(smb2_symlink_err_rsp), which is correct only when\nErrorContextCount == 0.\n\nWith at least one error context the symlink data sits 8 bytes deeper,\nand each skipped non-matching context shifts it further by 8 +\nALIGN(ErrorDataLength, 8).  The check is too short, allowing the\nsubstitute name read to run past iov_len.  The out-of-bound heap bytes\nare UTF-16-decoded into the symlink target and returned to userspace via\nreadlink(2).\n\nFix this all up by making the loops test require the full context header\nto fit, rejecting sym if its header runs past end, and bound the\nsubstitute name against the actual position of sym->PathBuffer rather\nthan a fixed offset.\n\nBecause sub_offs and sub_len are 16bits, the pointer math will not\noverflow here with the new greater-than."}],"providerMetadata":{"dateUpdated":"2026-04-24T14:42:33.453Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/e0dd90d14cbbf318157ea8e3fb62ee68a28655ed"},{"url":"https://git.kernel.org/stable/c/781902e069f4ecb6c3b83502f181972c1446110a"},{"url":"https://git.kernel.org/stable/c/a66ef2e7ed837325c5600f8617d5ee0a0a149fdd"}],"title":"smb: client: fix OOB reads parsing symlink error response","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31613","datePublished":"2026-04-24T14:42:33.453Z","dateReserved":"2026-03-09T15:48:24.123Z","dateUpdated":"2026-04-24T14:42:33.453Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-24 15:16:40","lastModifiedDate":"2026-04-24 17:51:40","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31613","Ordinal":"1","Title":"smb: client: fix OOB reads parsing symlink error response","CVE":"CVE-2026-31613","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31613","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB reads parsing symlink error response\n\nWhen a CREATE returns STATUS_STOPPED_ON_SYMLINK, smb2_check_message()\nreturns success without any length validation, leaving the symlink\nparsers as the only defense against an untrusted server.\n\nsymlink_data() walks SMB 3.1.1 error contexts with the loop test \"p <\nend\", but reads p->ErrorId at offset 4 and p->ErrorDataLength at offset\n0.  When the server-controlled ErrorDataLength advances p to within 1-7\nbytes of end, the next iteration will read past it.  When the matching\ncontext is found, sym->SymLinkErrorTag is read at offset 4 from\np->ErrorContextData with no check that the symlink header itself fits.\n\nsmb2_parse_symlink_response() then bounds-checks the substitute name\nusing SMB2_SYMLINK_STRUCT_SIZE as the offset of PathBuffer from\niov_base.  That value is computed as sizeof(smb2_err_rsp) +\nsizeof(smb2_symlink_err_rsp), which is correct only when\nErrorContextCount == 0.\n\nWith at least one error context the symlink data sits 8 bytes deeper,\nand each skipped non-matching context shifts it further by 8 +\nALIGN(ErrorDataLength, 8).  The check is too short, allowing the\nsubstitute name read to run past iov_len.  The out-of-bound heap bytes\nare UTF-16-decoded into the symlink target and returned to userspace via\nreadlink(2).\n\nFix this all up by making the loops test require the full context header\nto fit, rejecting sym if its header runs past end, and bound the\nsubstitute name against the actual position of sym->PathBuffer rather\nthan a fixed offset.\n\nBecause sub_offs and sub_len are 16bits, the pointer math will not\noverflow here with the new greater-than.","Type":"Description","Title":"smb: client: fix OOB reads parsing symlink error response"}]}}}