{"api_version":"1","generated_at":"2026-10-31T15:45:45+00:00","cve":"CVE-2026-99110","urls":{"html":"https://cve.report/CVE-2026-99110","api":"https://cve.report/api/cve/CVE-2026-99110.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99110","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99110"},"summary":{"title":"smb: client: fix heap overflow in cifs_do_set_acl()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in cifs_do_set_acl()\n\ncifs_set_acl() validates ACL size using posix_acl_xattr_size():\n\n        4 + (count * 8)  // 4-byte header + 8 bytes per ACE\n\ncifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS\nwire format into the same buffer:\n\n        6 + (count * 10)  // 6-byte header + 10 bytes per ACE\n\nAn ACL that passes the xattr-based check in cifs_set_acl() can\noverflow the heap when posix_acl_to_cifs() writes the larger CIFS\nformat.\n\nValidate the CIFS format size against the remaining buffer space and\nUSHRT_MAX before converting--data_count is __u16, so sizes above\nUSHRT_MAX truncate the on-wire packet length, causing the server to\napply a partial ACL.  Replace MaxDataCount = 1000 with\nmin(CIFSMaxBufSize, USHRT_MAX).","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:30","updated_at":"2026-10-31 13:17:55"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/596b4062e6c75bdd85a7f2b7f2087a872dc420ac","name":"https://git.kernel.org/stable/c/596b4062e6c75bdd85a7f2b7f2087a872dc420ac","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9312a00215602ba028495ef3fa00fb84af0478e0","name":"https://git.kernel.org/stable/c/9312a00215602ba028495ef3fa00fb84af0478e0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/68652afb9b9adf70125971abee9b95341e042249","name":"https://git.kernel.org/stable/c/68652afb9b9adf70125971abee9b95341e042249","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d96f3365ce61c5f39602955af43c8174548dee98","name":"https://git.kernel.org/stable/c/d96f3365ce61c5f39602955af43c8174548dee98","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1dac61e2c29d1a71784604b48cf3b1234a65ec29","name":"https://git.kernel.org/stable/c/1dac61e2c29d1a71784604b48cf3b1234a65ec29","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99110","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99110","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dc1af4c4b4721abfa07b351063825acc7e69cc66 68652afb9b9adf70125971abee9b95341e042249 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dc1af4c4b4721abfa07b351063825acc7e69cc66 9312a00215602ba028495ef3fa00fb84af0478e0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dc1af4c4b4721abfa07b351063825acc7e69cc66 d96f3365ce61c5f39602955af43c8174548dee98 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dc1af4c4b4721abfa07b351063825acc7e69cc66 596b4062e6c75bdd85a7f2b7f2087a872dc420ac git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"99110","cve":"CVE-2026-99110","epss":"0.001840000","percentile":"0.079980000","score_date":"2026-10-30","updated_at":"2026-10-31 00:01:13"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/client/cifssmb.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"68652afb9b9adf70125971abee9b95341e042249","status":"affected","version":"dc1af4c4b4721abfa07b351063825acc7e69cc66","versionType":"git"},{"lessThan":"9312a00215602ba028495ef3fa00fb84af0478e0","status":"affected","version":"dc1af4c4b4721abfa07b351063825acc7e69cc66","versionType":"git"},{"lessThan":"d96f3365ce61c5f39602955af43c8174548dee98","status":"affected","version":"dc1af4c4b4721abfa07b351063825acc7e69cc66","versionType":"git"},{"lessThan":"596b4062e6c75bdd85a7f2b7f2087a872dc420ac","status":"affected","version":"dc1af4c4b4721abfa07b351063825acc7e69cc66","versionType":"git"},{"lessThan":"1dac61e2c29d1a71784604b48cf3b1234a65ec29","status":"affected","version":"dc1af4c4b4721abfa07b351063825acc7e69cc66","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/cifssmb.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.2"},{"lessThan":"6.2","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.161","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.115","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.59","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.13","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.161","versionStartIncluding":"6.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.115","versionStartIncluding":"6.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.59","versionStartIncluding":"6.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.13","versionStartIncluding":"6.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in cifs_do_set_acl()\n\ncifs_set_acl() validates ACL size using posix_acl_xattr_size():\n\n        4 + (count * 8)  // 4-byte header + 8 bytes per ACE\n\ncifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS\nwire format into the same buffer:\n\n        6 + (count * 10)  // 6-byte header + 10 bytes per ACE\n\nAn ACL that passes the xattr-based check in cifs_set_acl() can\noverflow the heap when posix_acl_to_cifs() writes the larger CIFS\nformat.\n\nValidate the CIFS format size against the remaining buffer space and\nUSHRT_MAX before converting--data_count is __u16, so sizes above\nUSHRT_MAX truncate the on-wire packet length, causing the server to\napply a partial ACL.  Replace MaxDataCount = 1000 with\nmin(CIFSMaxBufSize, USHRT_MAX)."}],"metrics":[{"cvssV3_1":{"baseScore":7,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - setxattr(2) on system.posix_acl_access/default flows through do_set_acl() → set_posix_acl() → cifs_set_acl() → patched cifs_do_set_acl(); the oversized ACL originates in the local xattr, while SMB_COM_TRANSACTION2 is only an outbound request.\nAC:H - The copy is deterministic once reached, but it requires default-off CONFIG_CIFS_POSIX, an SMB1 mount, and server negotiation of CIFS_UNIX_POSIX_ACL_CAP to set SB_POSIXACL. An unprivileged local attacker cannot create that mount or capability state.\nPR:L - set_posix_acl() gates the path with inode_owner_or_capable(), so an ordinary user who owns a file on the mounted share can submit the ACL without capabilities; on a non-multiuser mount cifs_sb_tlink() simply reuses the master tcon.\nUI:N - The attacker directly invokes setxattr() or fsetxattr() on their CIFS inode, causing cifs_set_acl() to run without any separate victim action after the qualifying mount exists.\nS:U - posix_acl_to_cifs() overwrites the client kernel's cifs_request slab, and any resulting kernel compromise remains within the same host security authority rather than crossing a VM, IOMMU, or sandbox boundary.\nC:H - cifs_init_ace() emits attacker-shaped 10-byte tag, permission, and uid/gid records past the cifs_request object; with the supported 8KiB CIFSMaxBufSize, the overflow reaches neighboring request objects. This controllable slab corruption can be groomed into reuse or overlap and kernel-memory disclosure.\nI:H - posix_acl_to_cifs() writes a multi-kilobyte out-of-bounds stream whose ACE tags, permissions, and 32-bit uid/gid values are caller-selected; corrupting adjacent request or allocator state provides heap-write and control-flow-hijack potential.\nA:H - With default CIFSMaxBufSize=16384, 2047 valid entries pass cifs_set_acl()'s 16380-byte check but make posix_acl_to_cifs() write 20476 bytes, nearly 4KiB beyond the 16588-byte allocation before SendReceive() rejects the frame. Repeated calls can oops or panic the kernel."}]}],"providerMetadata":{"dateUpdated":"2026-10-31T12:43:03.377Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/68652afb9b9adf70125971abee9b95341e042249"},{"url":"https://git.kernel.org/stable/c/9312a00215602ba028495ef3fa00fb84af0478e0"},{"url":"https://git.kernel.org/stable/c/d96f3365ce61c5f39602955af43c8174548dee98"},{"url":"https://git.kernel.org/stable/c/596b4062e6c75bdd85a7f2b7f2087a872dc420ac"},{"url":"https://git.kernel.org/stable/c/1dac61e2c29d1a71784604b48cf3b1234a65ec29"}],"title":"smb: client: fix heap overflow in cifs_do_set_acl()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99110","datePublished":"2026-10-28T10:34:28.239Z","dateReserved":"2026-09-25T10:25:14.392Z","dateUpdated":"2026-10-31T12:43:03.377Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-28 11:17:30","lastModifiedDate":"2026-10-31 13:17:55","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99110","Ordinal":"1","Title":"smb: client: fix heap overflow in cifs_do_set_acl()","CVE":"CVE-2026-99110","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99110","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in cifs_do_set_acl()\n\ncifs_set_acl() validates ACL size using posix_acl_xattr_size():\n\n        4 + (count * 8)  // 4-byte header + 8 bytes per ACE\n\ncifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS\nwire format into the same buffer:\n\n        6 + (count * 10)  // 6-byte header + 10 bytes per ACE\n\nAn ACL that passes the xattr-based check in cifs_set_acl() can\noverflow the heap when posix_acl_to_cifs() writes the larger CIFS\nformat.\n\nValidate the CIFS format size against the remaining buffer space and\nUSHRT_MAX before converting--data_count is __u16, so sizes above\nUSHRT_MAX truncate the on-wire packet length, causing the server to\napply a partial ACL.  Replace MaxDataCount = 1000 with\nmin(CIFSMaxBufSize, USHRT_MAX).","Type":"Description","Title":"smb: client: fix heap overflow in cifs_do_set_acl()"}]}}}