{"api_version":"1","generated_at":"2026-07-23T12:59:14+00:00","cve":"CVE-2026-31437","urls":{"html":"https://cve.report/CVE-2026-31437","api":"https://cve.report/api/cve/CVE-2026-31437.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31437","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31437"},"summary":{"title":"netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry\n\nWhen a write subrequest is marked NETFS_SREQ_NEED_RETRY, the retry path\nin netfs_unbuffered_write() unconditionally calls stream->prepare_write()\nwithout checking if it is NULL.\n\nFilesystems such as 9P do not set the prepare_write operation, so\nstream->prepare_write remains NULL. When get_user_pages() fails with\n-EFAULT and the subrequest is flagged for retry, this results in a NULL\npointer dereference at fs/netfs/direct_write.c:189.\n\nFix this by mirroring the pattern already used in write_retry.c: if\nstream->prepare_write is NULL, skip renegotiation and directly reissue\nthe subrequest via netfs_reissue_write(), which handles iterator reset,\nIN_PROGRESS flag, stats update and reissue internally.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-04-22 14:16:36","updated_at":"2026-05-19 22:09:14"},"problem_types":["CWE-476"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"5.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}}],"references":[{"url":"https://git.kernel.org/stable/c/a4d1b4ba9754bac3efebd06f583a44a7af52c0ab","name":"https://git.kernel.org/stable/c/a4d1b4ba9754bac3efebd06f583a44a7af52c0ab","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e9075e420a1eb3b52c60f3b95893a55e77419ce8","name":"https://git.kernel.org/stable/c/e9075e420a1eb3b52c60f3b95893a55e77419ce8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7a5482f5ce891decbf36f2e6fab1e9fc4a76a684","name":"https://git.kernel.org/stable/c/7a5482f5ce891decbf36f2e6fab1e9fc4a76a684","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31437","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31437","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 72d08d2839649d1c5efbe375751f4473fa4486af a4d1b4ba9754bac3efebd06f583a44a7af52c0ab git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0 7a5482f5ce891decbf36f2e6fab1e9fc4a76a684 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0b4c7a49137ed21279f354eb59f49ddae8dffc2 e9075e420a1eb3b52c60f3b95893a55e77419ce8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.17 6.18.21 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.19.7 6.19.11 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2026","cve_id":"31437","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"31437","cve":"CVE-2026-31437","epss":"0.000170000","percentile":"0.040700000","score_date":"2026-04-26","updated_at":"2026-04-27 00:09:42"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/netfs/direct_write.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a4d1b4ba9754bac3efebd06f583a44a7af52c0ab","status":"affected","version":"72d08d2839649d1c5efbe375751f4473fa4486af","versionType":"git"},{"lessThan":"7a5482f5ce891decbf36f2e6fab1e9fc4a76a684","status":"affected","version":"0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0","versionType":"git"},{"lessThan":"e9075e420a1eb3b52c60f3b95893a55e77419ce8","status":"affected","version":"a0b4c7a49137ed21279f354eb59f49ddae8dffc2","versionType":"git"}]},{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/netfs/direct_write.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"6.18.21","status":"affected","version":"6.18.17","versionType":"semver"},{"lessThan":"6.19.11","status":"affected","version":"6.19.7","versionType":"semver"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.21","versionStartIncluding":"6.18.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.11","versionStartIncluding":"6.19.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry\n\nWhen a write subrequest is marked NETFS_SREQ_NEED_RETRY, the retry path\nin netfs_unbuffered_write() unconditionally calls stream->prepare_write()\nwithout checking if it is NULL.\n\nFilesystems such as 9P do not set the prepare_write operation, so\nstream->prepare_write remains NULL. When get_user_pages() fails with\n-EFAULT and the subrequest is flagged for retry, this results in a NULL\npointer dereference at fs/netfs/direct_write.c:189.\n\nFix this by mirroring the pattern already used in write_retry.c: if\nstream->prepare_write is NULL, skip renegotiation and directly reissue\nthe subrequest via netfs_reissue_write(), which handles iterator reset,\nIN_PROGRESS flag, stats update and reissue internally."}],"providerMetadata":{"dateUpdated":"2026-05-11T22:08:41.432Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a4d1b4ba9754bac3efebd06f583a44a7af52c0ab"},{"url":"https://git.kernel.org/stable/c/7a5482f5ce891decbf36f2e6fab1e9fc4a76a684"},{"url":"https://git.kernel.org/stable/c/e9075e420a1eb3b52c60f3b95893a55e77419ce8"}],"title":"netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31437","datePublished":"2026-04-22T13:53:36.361Z","dateReserved":"2026-03-09T15:48:24.090Z","dateUpdated":"2026-05-11T22:08:41.432Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-22 14:16:36","lastModifiedDate":"2026-05-19 22:09:14","problem_types":["CWE-476"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18.17","versionEndExcluding":"6.18.21","matchCriteriaId":"3EF23CE5-8E2E-47D1-9B2C-449AA5BB1870"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19.7","versionEndExcluding":"6.19.11","matchCriteriaId":"0F154E5F-DF7A-4EB9-BAFA-13EC093D679A"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31437","Ordinal":"1","Title":"netfs: Fix NULL pointer dereference in netfs_unbuffered_write() ","CVE":"CVE-2026-31437","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31437","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry\n\nWhen a write subrequest is marked NETFS_SREQ_NEED_RETRY, the retry path\nin netfs_unbuffered_write() unconditionally calls stream->prepare_write()\nwithout checking if it is NULL.\n\nFilesystems such as 9P do not set the prepare_write operation, so\nstream->prepare_write remains NULL. When get_user_pages() fails with\n-EFAULT and the subrequest is flagged for retry, this results in a NULL\npointer dereference at fs/netfs/direct_write.c:189.\n\nFix this by mirroring the pattern already used in write_retry.c: if\nstream->prepare_write is NULL, skip renegotiation and directly reissue\nthe subrequest via netfs_reissue_write(), which handles iterator reset,\nIN_PROGRESS flag, stats update and reissue internally.","Type":"Description","Title":"netfs: Fix NULL pointer dereference in netfs_unbuffered_write() "}]}}}