{"api_version":"1","generated_at":"2026-09-12T04:34:23+00:00","cve":"CVE-2026-89711","urls":{"html":"https://cve.report/CVE-2026-89711","api":"https://cve.report/api/cve/CVE-2026-89711.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89711","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89711"},"summary":{"title":"NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:58","updated_at":"2026-09-11 20:19:58"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/a275de3bac5635514ca830f2e46b5ff0e66b5c4c","name":"https://git.kernel.org/stable/c/a275de3bac5635514ca830f2e46b5ff0e66b5c4c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e","name":"https://git.kernel.org/stable/c/aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b55b4d880bb080fa10eb08ba21a5d8679b8102fe","name":"https://git.kernel.org/stable/c/b55b4d880bb080fa10eb08ba21a5d8679b8102fe","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7ef182a8fe9c12b0d936880b1e504840639aa009","name":"https://git.kernel.org/stable/c/7ef182a8fe9c12b0d936880b1e504840639aa009","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89711","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89711","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c b55b4d880bb080fa10eb08ba21a5d8679b8102fe git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c 7ef182a8fe9c12b0d936880b1e504840639aa009 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c a275de3bac5635514ca830f2e46b5ff0e66b5c4c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.8","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.8 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"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"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"4.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:46:26.269Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89711","datePublished":"2026-09-11T19:46:26.269Z","dateReserved":"2026-09-11T19:38:34.751Z","dateUpdated":"2026-09-11T19:46:26.269Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:58","lastModifiedDate":"2026-09-11 20:19:58","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89711","Ordinal":"1","Title":"NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check","CVE":"CVE-2026-89711","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89711","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check"}]}}}