{"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"}}}}