{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-99110", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.392Z", "datePublished": "2026-10-28T10:34:28.239Z", "dateUpdated": "2026-10-31T12:43:03.377Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-31T12:43:03.377Z" }, "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": { "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" }, "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/cifssmb.c" ], "versions": [ { "version": "dc1af4c4b4721abfa07b351063825acc7e69cc66", "lessThan": "68652afb9b9adf70125971abee9b95341e042249", "status": "affected", "versionType": "git" }, { "version": "dc1af4c4b4721abfa07b351063825acc7e69cc66", "lessThan": "9312a00215602ba028495ef3fa00fb84af0478e0", "status": "affected", "versionType": "git" }, { "version": "dc1af4c4b4721abfa07b351063825acc7e69cc66", "lessThan": "d96f3365ce61c5f39602955af43c8174548dee98", "status": "affected", "versionType": "git" }, { "version": "dc1af4c4b4721abfa07b351063825acc7e69cc66", "lessThan": "596b4062e6c75bdd85a7f2b7f2087a872dc420ac", "status": "affected", "versionType": "git" }, { "version": "dc1af4c4b4721abfa07b351063825acc7e69cc66", "lessThan": "1dac61e2c29d1a71784604b48cf3b1234a65ec29", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/cifssmb.c" ], "versions": [ { "version": "6.2", "status": "affected" }, { "version": "0", "lessThan": "6.2", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.161", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.115", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.59", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.13", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.161" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.12.115" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.18.59" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "7.2.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "7.3" } ] } ] } ], "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" } } } }