{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-99131", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.394Z", "datePublished": "2026-10-28T10:34:45.102Z", "dateUpdated": "2026-10-31T12:43:34.118Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-31T12:43:34.118Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: fix capability check in xfs\n\nAn user reported a bug where he managed to evade group's quota\nby changing a file's gid to a different group id the same user\nbelonged to, even though quotas were enforced on both gids and the\nfile's size was big enough to exceed the quota's hardlimit.\n\nCommit eba0549bc7d1 replaced a capable() call by a\nhas_capability_noaudit() to prevent unnecessary selinux audit messages.\nTurns out that both calls have slightly different semantics even though\ntheir documentation seems similar. Where in a nutshell:\n\ncapable() - Tests the task's effective credentials\nhas_ns_capability_noaudit() - Tests the task's real credentials\n\nThis most of the time has no practical difference but in some cases like\nchanging attrs (specifically group id in this case) through a NFS client\nthis will allow the quota code to use XFS_QMOPT_FORCE_RES, effectively\nbypassing quota accounting checks.\n\nUsing instead ns_capable_noaudit() should fix this issue and prevent\nselinux audit messages.\n\nThis also fix the remaining calls to has_capability_noaudit()" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - An NFSv4 COMPOUND/SETATTR request carries FATTR4_OWNER_GROUP; nfsd4_decode_setattr() sets ATTR_GID, and nfsd4_setattr()->nfsd_setattr()->notify_change()->xfs_vn_setattr() reaches the patched xfs_setattr_nonsize(). NFS is routable, so the vector is Network.\nAC:L - The attacker controls the deterministic sequence: AUTH_SYS credentials assert both groups, NFS WRITE fills the source group's quota, and SETATTR moves each file to the over-limit destination group. No race or external state transition is required.\nPR:N - svcauth_unix_accept() accepts the uid, gid, and supplementary groups asserted in an AUTH_SYS RPC without account verification, and nfsd_setuser() installs them as subjective credentials. chgrp_ok() then requires only the asserted owner identity and destination-group membership.\nUI:N - The remote client creates and fills the file and sends the SETATTR group change itself; neither nfsd_setattr() nor xfs_setattr_nonsize() requires a separate victim action.\nS:U - xfs_trans_dqresv() skips a quota check and xfs_qm_vop_chown() updates dquots within the same host XFS security authority; no VM, sandbox, or other security boundary is crossed.\nC:N - XFS_QMOPT_FORCE_RES only bypasses the limit branch in xfs_trans_dqresv(), after which quota counters and inode ownership are updated; the path performs no out-of-bounds read or disclosure of kernel or other-file data.\nI:L - With XFS_QMOPT_FORCE_RES set, xfs_trans_dqresv() omits the hard-limit test and xfs_qm_vop_chown() charges blocks and inodes to an already over-limit group. This defeats quota policy and modifies resource accounting, but provides no arbitrary write or control over other users' file contents.\nA:H - xfs_qm_vop_chown() debits the source dquot and, after forced reservation, credits the already over-limit destination; repeating NFS writes and group changes can consume the entire XFS volume. Full-volume exhaustion denies allocations to all users and services on that filesystem." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/xfs/xfs_fsmap.c", "fs/xfs/xfs_ioctl.c", "fs/xfs/xfs_iops.c" ], "versions": [ { "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "lessThan": "29f994db0447104a7a52fb6495193c80007cb66a", "status": "affected", "versionType": "git" }, { "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "lessThan": "e84bfb08016496ec5ce09a5ef9c813f23c060781", "status": "affected", "versionType": "git" }, { "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "lessThan": "87881f816ab721d8a727cba20c36b9c71b489c8e", "status": "affected", "versionType": "git" }, { "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "lessThan": "19a1a22029ad3ae3604c763af6bd1195cb73648f", "status": "affected", "versionType": "git" }, { "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "lessThan": "7809ac0161c7c5f52ed348fb1ec683b2b454a83e", "status": "affected", "versionType": "git" }, { "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "lessThan": "e2f62a9744ebad3bcb6347a648e615026e9efeff", "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/xfs/xfs_fsmap.c", "fs/xfs/xfs_ioctl.c", "fs/xfs/xfs_iops.c" ], "versions": [ { "version": "5.18", "status": "affected" }, { "version": "0", "lessThan": "5.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.191", "lessThanOrEqual": "6.1.*", "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": "5.18", "versionEndExcluding": "6.1.191" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.6.161" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.12.115" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.18.59" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "7.2.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/29f994db0447104a7a52fb6495193c80007cb66a" }, { "url": "https://git.kernel.org/stable/c/e84bfb08016496ec5ce09a5ef9c813f23c060781" }, { "url": "https://git.kernel.org/stable/c/87881f816ab721d8a727cba20c36b9c71b489c8e" }, { "url": "https://git.kernel.org/stable/c/19a1a22029ad3ae3604c763af6bd1195cb73648f" }, { "url": "https://git.kernel.org/stable/c/7809ac0161c7c5f52ed348fb1ec683b2b454a83e" }, { "url": "https://git.kernel.org/stable/c/e2f62a9744ebad3bcb6347a648e615026e9efeff" } ], "title": "xfs: fix capability check in xfs", "x_generator": { "engine": "bippy-1.2.0" } } } }