CVE-2026-99131

{"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"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/xfs/xfs_fsmap.c", "fs/xfs/xfs_ioctl.c", "fs/xfs/xfs_iops.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "29f994db0447104a7a52fb6495193c80007cb66a", "status": "affected", "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "versionType": "git"}, {"lessThan": "e84bfb08016496ec5ce09a5ef9c813f23c060781", "status": "affected", "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "versionType": "git"}, {"lessThan": "87881f816ab721d8a727cba20c36b9c71b489c8e", "status": "affected", "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "versionType": "git"}, {"lessThan": "19a1a22029ad3ae3604c763af6bd1195cb73648f", "status": "affected", "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "versionType": "git"}, {"lessThan": "7809ac0161c7c5f52ed348fb1ec683b2b454a83e", "status": "affected", "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "versionType": "git"}, {"lessThan": "e2f62a9744ebad3bcb6347a648e615026e9efeff", "status": "affected", "version": "eba0549bc7d100691c13384b774346b8aa9cf9a9", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/xfs/xfs_fsmap.c", "fs/xfs/xfs_ioctl.c", "fs/xfs/xfs_iops.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.18"}, {"lessThan": "5.18", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.191", "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"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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()"}], "id": "CVE-2026-99131", "lastModified": "2026-10-31T13:17:56.757", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 4.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-10-28T11:17:32.917", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/19a1a22029ad3ae3604c763af6bd1195cb73648f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/29f994db0447104a7a52fb6495193c80007cb66a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7809ac0161c7c5f52ed348fb1ec683b2b454a83e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/87881f816ab721d8a727cba20c36b9c71b489c8e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e2f62a9744ebad3bcb6347a648e615026e9efeff"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e84bfb08016496ec5ce09a5ef9c813f23c060781"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: kernel: xfs: Disk quota bypass via improper capability check", "id": "2562644", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2562644"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L", "status": "draft"}, "cwe": "CWE-770", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nxfs: fix capability check in xfs\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.\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:\ncapable() - Tests the task's effective credentials\nhas_ns_capability_noaudit() - Tests the task's real credentials\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.\nUsing instead ns_capable_noaudit() should fix this issue and prevent\nselinux audit messages.\nThis also fix the remaining calls to has_capability_noaudit()", "A flaw was found in the XFS file system in the Linux kernel. An improper capability check verified a task's real credentials instead of its effective credentials, causing the system to treat certain attribute modifications as privileged. A user, particularly when modifying file ownership over a Network File System (NFS) client, can exploit this flaw to bypass storage quota accounting and exceed enforced disk quota limits."], "name": "CVE-2026-99131", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-10-28T10:34:45Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-99131\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-99131\nhttps://git.kernel.org/stable/c/19a1a22029ad3ae3604c763af6bd1195cb73648f\nhttps://git.kernel.org/stable/c/7809ac0161c7c5f52ed348fb1ec683b2b454a83e\nhttps://git.kernel.org/stable/c/e2f62a9744ebad3bcb6347a648e615026e9efeff"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[eba0549bc7d100691c13384b774346b8aa9cf9a9,19a1a22029ad3ae3604c763af6bd1195cb73648f)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[eba0549bc7d100691c13384b774346b8aa9cf9a9,7809ac0161c7c5f52ed348fb1ec683b2b454a83e)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[eba0549bc7d100691c13384b774346b8aa9cf9a9,e2f62a9744ebad3bcb6347a648e615026e9efeff)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "5.18"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.18)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.59,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.13,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[eba0549bc7d100691c13384b774346b8aa9cf9a9,19a1a22029ad3ae3604c763af6bd1195cb73648f)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[eba0549bc7d100691c13384b774346b8aa9cf9a9,7809ac0161c7c5f52ed348fb1ec683b2b454a83e)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[eba0549bc7d100691c13384b774346b8aa9cf9a9,e2f62a9744ebad3bcb6347a648e615026e9efeff)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "5.18"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.18)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.59,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.13,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-10-28T11:45:09.959077+00:00", "updated": "2026-10-31T13:30:13.672756+00:00", "vendors": ["linux", "linux$PRODUCT$linux", "linux$PRODUCT$linux_kernel"]}