{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89711", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.751Z", "datePublished": "2026-09-11T19:46:26.269Z", "dateUpdated": "2026-09-11T19:46:26.269Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-11T19:46:26.269Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check\n\nThe header for commit e75b23f9e323 (\"nfsd: check d_can_lookup in\nfh_verify of directories\") details the assumption that justified\nadding the WARN_ON_ONCE to nfsd_mode_check(), that assumption is\ninvalid (in the case of NFS reexport).\n\nWhen NFSD exports an NFS filesystem it is very possible for\nnfsd_mode_check() to encounter a @dentry that doesn't have\ni_op->lookup (see nfs_fhget()'s NFS_ATTR_FATTR_MOUNTPOINT and\nNFS_ATTR_FATTR_V4_REFERRAL handling, and d_flags_for_inode()).\n\nSo remove nfsd_mode_check()'s WARN_ON_ONCE(). The nfserr_notdir\nreturn on that branch must stay. It guards the subsequent\nlookup_one_unlocked() -> __lookup_slow() path, which calls\ninode->i_op->lookup() with no NULL check, so returning nfserr_notdir\nis what keeps a client LOOKUP into such a @dentry from dereferencing\na NULL method pointer."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfsd/nfsfh.c"], "versions": [{"version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "lessThan": "b55b4d880bb080fa10eb08ba21a5d8679b8102fe", "status": "affected", "versionType": "git"}, {"version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "lessThan": "7ef182a8fe9c12b0d936880b1e504840639aa009", "status": "affected", "versionType": "git"}, {"version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "lessThan": "a275de3bac5635514ca830f2e46b5ff0e66b5c4c", "status": "affected", "versionType": "git"}, {"version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "lessThan": "aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e", "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/nfsd/nfsfh.c"], "versions": [{"version": "4.8", "status": "affected"}, {"version": "0", "lessThan": "4.8", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc1", "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": "4.8", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.8", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.8", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.8", "versionEndExcluding": "7.3-rc1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/b55b4d880bb080fa10eb08ba21a5d8679b8102fe"}, {"url": "https://git.kernel.org/stable/c/7ef182a8fe9c12b0d936880b1e504840639aa009"}, {"url": "https://git.kernel.org/stable/c/a275de3bac5635514ca830f2e46b5ff0e66b5c4c"}, {"url": "https://git.kernel.org/stable/c/aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e"}], "title": "NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/nfsd/nfsfh.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "b55b4d880bb080fa10eb08ba21a5d8679b8102fe", "status": "affected", "version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "versionType": "git"}, {"lessThan": "7ef182a8fe9c12b0d936880b1e504840639aa009", "status": "affected", "version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "versionType": "git"}, {"lessThan": "a275de3bac5635514ca830f2e46b5ff0e66b5c4c", "status": "affected", "version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "versionType": "git"}, {"lessThan": "aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e", "status": "affected", "version": "e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/nfsd/nfsfh.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.8"}, {"lessThan": "4.8", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.109", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3-rc1", "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\nNFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check\n\nThe header for commit e75b23f9e323 (\"nfsd: check d_can_lookup in\nfh_verify of directories\") details the assumption that justified\nadding the WARN_ON_ONCE to nfsd_mode_check(), that assumption is\ninvalid (in the case of NFS reexport).\n\nWhen NFSD exports an NFS filesystem it is very possible for\nnfsd_mode_check() to encounter a @dentry that doesn't have\ni_op->lookup (see nfs_fhget()'s NFS_ATTR_FATTR_MOUNTPOINT and\nNFS_ATTR_FATTR_V4_REFERRAL handling, and d_flags_for_inode()).\n\nSo remove nfsd_mode_check()'s WARN_ON_ONCE(). The nfserr_notdir\nreturn on that branch must stay. It guards the subsequent\nlookup_one_unlocked() -> __lookup_slow() path, which calls\ninode->i_op->lookup() with no NULL check, so returning nfserr_notdir\nis what keeps a client LOOKUP into such a @dentry from dereferencing\na NULL method pointer."}], "id": "CVE-2026-89711", "lastModified": "2026-09-11T20:19:58.500", "metrics": {}, "published": "2026-09-11T20:19:58.500", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7ef182a8fe9c12b0d936880b1e504840639aa009"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a275de3bac5635514ca830f2e46b5ff0e66b5c4c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b55b4d880bb080fa10eb08ba21a5d8679b8102fe"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: NFSD null pointer dereference via NFS reexport", "id": "2532508", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532508"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.9", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["A flaw was found in the Linux kernel's Network File System Daemon (NFSD). An invalid assumption in the `nfsd_mode_check()` function regarding directory lookup capabilities during NFS reexport could lead to a null pointer dereference. A remote attacker could exploit this by performing a LOOKUP operation on a specially crafted NFS reexport, potentially causing a system crash and resulting in a Denial of Service (DoS)."], "name": "CVE-2026-89711", "public_date": "2026-09-11T19:46:26Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89711\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89711\nhttps://git.kernel.org/stable/c/7ef182a8fe9c12b0d936880b1e504840639aa009\nhttps://git.kernel.org/stable/c/a275de3bac5635514ca830f2e46b5ff0e66b5c4c\nhttps://git.kernel.org/stable/c/aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e\nhttps://git.kernel.org/stable/c/b55b4d880bb080fa10eb08ba21a5d8679b8102fe"], "threat_severity": "Moderate"}

{"created": "2026-09-12T12:30:14.594991+00:00", "updated": "2026-09-12T18:00:13.209498+00:00", "vendors": []}