CVE-2026-31437

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-31437", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.090Z", "datePublished": "2026-04-22T13:53:36.361Z", "dateUpdated": "2026-05-11T22:08:41.432Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-11T22:08:41.432Z"}, "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."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/netfs/direct_write.c"], "versions": [{"version": "72d08d2839649d1c5efbe375751f4473fa4486af", "lessThan": "a4d1b4ba9754bac3efebd06f583a44a7af52c0ab", "status": "affected", "versionType": "git"}, {"version": "0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0", "lessThan": "7a5482f5ce891decbf36f2e6fab1e9fc4a76a684", "status": "affected", "versionType": "git"}, {"version": "a0b4c7a49137ed21279f354eb59f49ddae8dffc2", "lessThan": "e9075e420a1eb3b52c60f3b95893a55e77419ce8", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/netfs/direct_write.c"], "versions": [{"version": "6.18.17", "lessThan": "6.18.21", "status": "affected", "versionType": "semver"}, {"version": "6.19.7", "lessThan": "6.19.11", "status": "affected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.17", "versionEndExcluding": "6.18.21"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19.7", "versionEndExcluding": "6.19.11"}]}]}], "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"}}}}

{}

{"affected": [{"affectedData": [{"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"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "3EF23CE5-8E2E-47D1-9B2C-449AA5BB1870", "versionEndExcluding": "6.18.21", "versionStartIncluding": "6.18.17", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "0F154E5F-DF7A-4EB9-BAFA-13EC093D679A", "versionEndExcluding": "6.19.11", "versionStartIncluding": "6.19.7", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "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."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfs: Correcci\u00f3n de desreferencia de puntero NULL en netfs_unbuffered_write() al reintentar\n\nCuando una subsolicitud de escritura se marca como NETFS_SREQ_NEED_RETRY, la ruta de reintento en netfs_unbuffered_write() llama incondicionalmente a stream -> prepare_write() sin comprobar si es NULL.\n\nSistemas de archivos como 9P no establecen la operaci\u00f3n prepare_write, por lo que stream -> prepare_write permanece NULL. Cuando get_user_pages() falla con -EFAULT y la subsolicitud se marca para reintento, esto resulta en una desreferencia de puntero NULL en fs/netfs/direct_write.c:189.\n\nEsto se corrige replicando el patr\u00f3n ya utilizado en write_retry.c: si stream -> prepare_write es NULL, se omite la renegociaci\u00f3n y se reemite directamente la subsolicitud a trav\u00e9s de netfs_reissue_write(), que maneja internamente el reinicio del iterador, el indicador IN_PROGRESS, la actualizaci\u00f3n de estad\u00edsticas y la reemisi\u00f3n."}], "id": "CVE-2026-31437", "lastModified": "2026-11-11T23:10:00.263", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2026-04-22T14:16:36.980", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/7a5482f5ce891decbf36f2e6fab1e9fc4a76a684"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a4d1b4ba9754bac3efebd06f583a44a7af52c0ab"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e9075e420a1eb3b52c60f3b95893a55e77419ce8"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-476"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry", "id": "2460683", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2460683"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/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 netfs component. When a write operation is retried, the `netfs_unbuffered_write()` function can attempt to access a non-existent function, leading to a NULL pointer dereference. This vulnerability can be triggered by specific filesystem configurations, such as 9P, and could allow a local attacker to cause a system crash, resulting in a Denial of Service (DoS)."], "name": "CVE-2026-31437", "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": "Not affected", "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"}], "public_date": "2026-04-22T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-31437\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-31437\nhttps://lore.kernel.org/linux-cve-announce/2026042243-CVE-2026-31437-7cba@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[72d08d2839649d1c5efbe375751f4473fa4486af,a4d1b4ba9754bac3efebd06f583a44a7af52c0ab)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0,7a5482f5ce891decbf36f2e6fab1e9fc4a76a684)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[a0b4c7a49137ed21279f354eb59f49ddae8dffc2,e9075e420a1eb3b52c60f3b95893a55e77419ce8)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[6.18.17,6.18.21)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[6.19.7,6.19.11)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "analysis": {"en": {"generated_at": "2026-04-28T08:23:37.188327+00:00", "value": {"mitigation_remediation": ["Upgrade the kernel to a version that includes the commit adding a NULL check for stream->prepare_write in netfs_unbuffered_write.", "Reboot the system so that the updated kernel and modules are loaded.", "If an official patch is not yet available, avoid mounting 9P or other netfs filesystems that lack a prepare_write implementation until a fix is applied."], "summary": {"action": "Apply Patch", "impact": "Kernel crash leading to denial\u2011of\u2011service"}, "threat_synthesis": {"affected_systems": "All Linux kernel versions prior to the commit that introduces the NULL check are vulnerable. The issue affects any system that mounts a netfs implementation that does not provide a prepare_write function, notably the 9P filesystem. The vulnerability is present in every pre\u2011patch kernel revision and is fixed in kernels that incorporate the referenced commit URLs.", "description_and_impact": "In the Linux kernel, netfs_unbuffered_write() contains an unconditional call to stream->prepare_write when a write subrequest is marked NETFS_SREQ_NEED_RETRY. Filesystems such as 9P do not implement prepare_write, leaving the function pointer NULL. When get_user_pages() fails with \u2013EFAULT and the subrequest is flagged for retry, this results in a NULL pointer dereference at fs/netfs/direct_write.c:189, causing a kernel OOPS. This indicates a classic null pointer dereference weakness (CWE\u2011476) and can lead to an unprivileged kernel crash, providing a denial\u2011of\u2011service and a potential escalation surface if the fault is leveraged further.", "risk_and_exploitability": "The CVSS score of 5.5 indicates a medium severity, while the EPSS score of <\u202f1\u202f% suggests a low exploitation probability. The vulnerability is not listed in the CISA KEV catalog. Based on the description, it is inferred that a local attacker with write access to a netfs file can trigger the crash by causing a write failure and retry. The risk is therefore a local denial\u2011of\u2011service that could be exploited to destabilize the system or, in some circumstances, enable privilege escalation."}}}}, "created": "2026-04-22T16:45:21.256496+00:00", "updated": "2026-04-28T08:30:13.189082+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}