CVE-2026-99174

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-99174", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.399Z", "datePublished": "2026-10-28T10:35:28.758Z", "dateUpdated": "2026-10-30T12:42:37.969Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:42:37.969Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: free the sbi after a grace period\n\next4_get_link() follows a symlink that keeps its target in a data block\nin rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).\nThat reads s_mount_state in the ASSERT() of ext4_getblk() and again in\next4_es_lookup_extent(), and the lookup bumps the extent status hit or\nmiss counter, all through sb->s_fs_info.\n\next4_put_super() destroys those counters, clears sb->s_fs_info and frees\nthe sbi without waiting for a grace period. A pathwalk that is still in\next4_get_link() when the last reference to the mount goes away then\ndereferences a NULL s_fs_info, the freed sbi or the destroyed percpu\ncounters.\n\nWith a pathwalk held up in ext4_get_link() while the last reference\ngoes away:\n\n KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]\n RIP: 0010:ext4_getblk+0xf0/0x640\n Call Trace:\n <TASK>\n ext4_get_link+0x26c/0x410\n pick_link+0xf96/0x1780\n step_into_slowpath+0x9b8/0x1250\n path_lookupat+0x484/0xb00\n filename_lookup+0x1f1/0x5b0\n vfs_statx+0xd7/0x3b0\n vfs_fstatat+0x4d/0x90\n __do_sys_newfstatat+0xa0/0x100\n do_syscall_64+0x10e/0x5e0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nSo far that has been hard to hit. umount(2) waits for a grace period in\nnamespace_unlock() before it drops the mount, so only a mount whose last\nreference goes away elsewhere, like the close of a file or a chdir out of\na lazily unmounted directory, can race a walker.\n\nKeep sb->s_fs_info and free the sbi together with the extent status\ncounters after a grace period. Split the counters out of\next4_es_unregister_shrinker() for that. The shrinker still gets wasted\nin ext4_put_super(), the counters go with the sbi."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/ext4/ext4.h", "fs/ext4/extents-test.c", "fs/ext4/extents.c", "fs/ext4/extents_status.c", "fs/ext4/extents_status.h", "fs/ext4/super.c"], "versions": [{"version": "6493792d3299b3e33f887ef8a150099d271faf9c", "lessThan": "cf3bd5824c985b350d150bcd76698ee5e993fcba", "status": "affected", "versionType": "git"}, {"version": "6493792d3299b3e33f887ef8a150099d271faf9c", "lessThan": "b4b0598fad51a978fcbda9d55eef6b5bd3cbe7d8", "status": "affected", "versionType": "git"}, {"version": "6493792d3299b3e33f887ef8a150099d271faf9c", "lessThan": "4ce0e27ea610663a9cdc04e3bca38559147428d4", "status": "affected", "versionType": "git"}, {"version": "6493792d3299b3e33f887ef8a150099d271faf9c", "lessThan": "80d5db1686b05fad6f384be017714297d828a714", "status": "affected", "versionType": "git"}, {"version": "6493792d3299b3e33f887ef8a150099d271faf9c", "lessThan": "87d29b8b849738d52fe820d495fa0aa2d5a1ec82", "status": "affected", "versionType": "git"}, {"version": "6493792d3299b3e33f887ef8a150099d271faf9c", "lessThan": "c17b44266a1f9fcb49b894d4611d1254bf1aa313", "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/ext4/ext4.h", "fs/ext4/extents-test.c", "fs/ext4/extents.c", "fs/ext4/extents_status.c", "fs/ext4/extents_status.h", "fs/ext4/super.c"], "versions": [{"version": "5.19", "status": "affected"}, {"version": "0", "lessThan": "5.19", "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": "5.19", "versionEndExcluding": "6.1.191"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.161"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.115"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.18.59"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.2.13"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/cf3bd5824c985b350d150bcd76698ee5e993fcba"}, {"url": "https://git.kernel.org/stable/c/b4b0598fad51a978fcbda9d55eef6b5bd3cbe7d8"}, {"url": "https://git.kernel.org/stable/c/4ce0e27ea610663a9cdc04e3bca38559147428d4"}, {"url": "https://git.kernel.org/stable/c/80d5db1686b05fad6f384be017714297d828a714"}, {"url": "https://git.kernel.org/stable/c/87d29b8b849738d52fe820d495fa0aa2d5a1ec82"}, {"url": "https://git.kernel.org/stable/c/c17b44266a1f9fcb49b894d4611d1254bf1aa313"}], "title": "ext4: free the sbi after a grace period", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/ext4/ext4.h", "fs/ext4/extents-test.c", "fs/ext4/extents.c", "fs/ext4/extents_status.c", "fs/ext4/extents_status.h", "fs/ext4/super.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "cf3bd5824c985b350d150bcd76698ee5e993fcba", "status": "affected", "version": "6493792d3299b3e33f887ef8a150099d271faf9c", "versionType": "git"}, {"lessThan": "b4b0598fad51a978fcbda9d55eef6b5bd3cbe7d8", "status": "affected", "version": "6493792d3299b3e33f887ef8a150099d271faf9c", "versionType": "git"}, {"lessThan": "4ce0e27ea610663a9cdc04e3bca38559147428d4", "status": "affected", "version": "6493792d3299b3e33f887ef8a150099d271faf9c", "versionType": "git"}, {"lessThan": "80d5db1686b05fad6f384be017714297d828a714", "status": "affected", "version": "6493792d3299b3e33f887ef8a150099d271faf9c", "versionType": "git"}, {"lessThan": "87d29b8b849738d52fe820d495fa0aa2d5a1ec82", "status": "affected", "version": "6493792d3299b3e33f887ef8a150099d271faf9c", "versionType": "git"}, {"lessThan": "c17b44266a1f9fcb49b894d4611d1254bf1aa313", "status": "affected", "version": "6493792d3299b3e33f887ef8a150099d271faf9c", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/ext4/ext4.h", "fs/ext4/extents-test.c", "fs/ext4/extents.c", "fs/ext4/extents_status.c", "fs/ext4/extents_status.h", "fs/ext4/super.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.19"}, {"lessThan": "5.19", "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\next4: free the sbi after a grace period\n\next4_get_link() follows a symlink that keeps its target in a data block\nin rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).\nThat reads s_mount_state in the ASSERT() of ext4_getblk() and again in\next4_es_lookup_extent(), and the lookup bumps the extent status hit or\nmiss counter, all through sb->s_fs_info.\n\next4_put_super() destroys those counters, clears sb->s_fs_info and frees\nthe sbi without waiting for a grace period. A pathwalk that is still in\next4_get_link() when the last reference to the mount goes away then\ndereferences a NULL s_fs_info, the freed sbi or the destroyed percpu\ncounters.\n\nWith a pathwalk held up in ext4_get_link() while the last reference\ngoes away:\n\n KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]\n RIP: 0010:ext4_getblk+0xf0/0x640\n Call Trace:\n <TASK>\n ext4_get_link+0x26c/0x410\n pick_link+0xf96/0x1780\n step_into_slowpath+0x9b8/0x1250\n path_lookupat+0x484/0xb00\n filename_lookup+0x1f1/0x5b0\n vfs_statx+0xd7/0x3b0\n vfs_fstatat+0x4d/0x90\n __do_sys_newfstatat+0xa0/0x100\n do_syscall_64+0x10e/0x5e0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nSo far that has been hard to hit. umount(2) waits for a grace period in\nnamespace_unlock() before it drops the mount, so only a mount whose last\nreference goes away elsewhere, like the close of a file or a chdir out of\na lazily unmounted directory, can race a walker.\n\nKeep sb->s_fs_info and free the sbi together with the extent status\ncounters after a grace period. Split the counters out of\next4_es_unregister_shrinker() for that. The shrinker still gets wasted\nin ext4_put_super(), the counters go with the sbi."}], "id": "CVE-2026-99174", "lastModified": "2026-10-30T13:21:51.000", "metrics": {}, "published": "2026-10-28T11:17:38.030", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4ce0e27ea610663a9cdc04e3bca38559147428d4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/80d5db1686b05fad6f384be017714297d828a714"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/87d29b8b849738d52fe820d495fa0aa2d5a1ec82"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b4b0598fad51a978fcbda9d55eef6b5bd3cbe7d8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c17b44266a1f9fcb49b894d4611d1254bf1aa313"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/cf3bd5824c985b350d150bcd76698ee5e993fcba"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: ext4: free the sbi after a grace period", "id": "2562775", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2562775"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.1", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["In the Linux kernel, the following vulnerability has been resolved:\next4: free the sbi after a grace period\next4_get_link() follows a symlink that keeps its target in a data block\nin rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).\nThat reads s_mount_state in the ASSERT() of ext4_getblk() and again in\next4_es_lookup_extent(), and the lookup bumps the extent status hit or\nmiss counter, all through sb->s_fs_info.\next4_put_super() destroys those counters, clears sb->s_fs_info and frees\nthe sbi without waiting for a grace period. A pathwalk that is still in\next4_get_link() when the last reference to the mount goes away then\ndereferences a NULL s_fs_info, the freed sbi or the destroyed percpu\ncounters.\nWith a pathwalk held up in ext4_get_link() while the last reference\ngoes away:\nKASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]\nRIP: 0010:ext4_getblk+0xf0/0x640\nCall Trace:\n<TASK>\next4_get_link+0x26c/0x410\npick_link+0xf96/0x1780\nstep_into_slowpath+0x9b8/0x1250\npath_lookupat+0x484/0xb00\nfilename_lookup+0x1f1/0x5b0\nvfs_statx+0xd7/0x3b0\nvfs_fstatat+0x4d/0x90\n__do_sys_newfstatat+0xa0/0x100\ndo_syscall_64+0x10e/0x5e0\nentry_SYSCALL_64_after_hwframe+0x77/0x7f\nSo far that has been hard to hit. umount(2) waits for a grace period in\nnamespace_unlock() before it drops the mount, so only a mount whose last\nreference goes away elsewhere, like the close of a file or a chdir out of\na lazily unmounted directory, can race a walker.\nKeep sb->s_fs_info and free the sbi together with the extent status\ncounters after a grace period. Split the counters out of\next4_es_unregister_shrinker() for that. The shrinker still gets wasted\nin ext4_put_super(), the counters go with the sbi.", "A flaw was found in the Linux kernel's ext4 file system. A local user could exploit a race condition during concurrent file path lookup and filesystem unmount operations. When resolving a symbolic link as the filesystem's last mount reference is released, the kernel may dereference a null pointer or access previously freed memory, leading to a kernel crash and resulting in a Denial of Service (DoS)."], "name": "CVE-2026-99174", "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": "Out of support scope", "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": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "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": "2026-10-28T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-99174\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-99174\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99174.mbox"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6493792d3299b3e33f887ef8a150099d271faf9c,80d5db1686b05fad6f384be017714297d828a714)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6493792d3299b3e33f887ef8a150099d271faf9c,87d29b8b849738d52fe820d495fa0aa2d5a1ec82)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6493792d3299b3e33f887ef8a150099d271faf9c,c17b44266a1f9fcb49b894d4611d1254bf1aa313)"}}], "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": "5.19"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.19)"}}, {"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": "[6493792d3299b3e33f887ef8a150099d271faf9c,80d5db1686b05fad6f384be017714297d828a714)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6493792d3299b3e33f887ef8a150099d271faf9c,87d29b8b849738d52fe820d495fa0aa2d5a1ec82)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6493792d3299b3e33f887ef8a150099d271faf9c,c17b44266a1f9fcb49b894d4611d1254bf1aa313)"}}], "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": "5.19"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.19)"}}, {"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": "2026-10-28T12:00:22.512759+00:00", "updated": "2026-10-29T16:00:07.466260+00:00", "vendors": ["linux", "linux$PRODUCT$linux", "linux$PRODUCT$linux_kernel"]}