CVE-2025-39723

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-39723", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.117Z", "datePublished": "2025-09-05T17:21:31.137Z", "dateUpdated": "2026-08-05T12:04:52.373Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:04:52.373Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix unbuffered write error handling\n\nIf all the subrequests in an unbuffered write stream fail, the subrequest\ncollector doesn't update the stream->transferred value and it retains its\ninitial LONG_MAX value. Unfortunately, if all active streams fail, then we\ntake the smallest value of { LONG_MAX, LONG_MAX, ... } as the value to set\nin wreq->transferred - which is then returned from ->write_iter().\n\nLONG_MAX was chosen as the initial value so that all the streams can be\nquickly assessed by taking the smallest value of all stream->transferred -\nbut this only works if we've set any of them.\n\nFix this by adding a flag to indicate whether the value in\nstream->transferred is valid and checking that when we integrate the\nvalues. stream->transferred can then be initialised to zero.\n\nThis was found by running the generic/750 xfstest against cifs with\ncache=none. It splices data to the target file. Once (if) it has used up\nall the available scratch space, the writes start failing with ENOSPC.\nThis causes ->write_iter() to fail. However, it was returning\nwreq->transferred, i.e. LONG_MAX, rather than an error (because it thought\nthe amount transferred was non-zero) and iter_file_splice_write() would\nthen try to clean up that amount of pipe bufferage - leading to an oops\nwhen it overran. The kernel log showed:\n\n CIFS: VFS: Send error in write = -28\n\nfollowed by:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000008\n\nwith:\n\n RIP: 0010:iter_file_splice_write+0x3a4/0x520\n do_splice+0x197/0x4e0\n\nor:\n\n RIP: 0010:pipe_buf_release (include/linux/pipe_fs_i.h:282)\n iter_file_splice_write (fs/splice.c:755)\n\nAlso put a warning check into splice to announce if ->write_iter() returned\nthat it had written more than it was asked to."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H", "baseScore": 7.1, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:N - The netfs write collector processes write results derived from a remote SMB/9p server's responses, and the arming condition (every write subrequest failing) is entirely under the remote server's control \u2014 a malicious, compromised, or MITM'd file server simply returns STATUS_DISK_FULL/ACCESS_DENIED for the writes and the client kernel oopses. The vulnerable component is bound to the network stack via the cifs/9p transport.\nAC:L - The failure is deterministic: LONG_MAX always exceeds the total bytes held in the pipe, so the splice cleanup loop unconditionally runs past the valid buffers into a slot with NULL ops and faults. No race, no memory-layout dependency, no non-default config (cifs/9p with cache=none, or any O_DIRECT open).\nPR:N - A remote file server needs no credentials or privileges on the victim client to return write errors; in the equivalent local framing an ordinary unprivileged user with write access to the mount triggers it via splice()/cp with no capabilities at all.\nUI:R - The remote attacker cannot initiate the transfer itself \u2014 a client-side process must perform a splice-based write (splice/sendfile/copy_file_range, e.g. a routine `cp` onto the mounted share) for the bogus LONG_MAX return to reach iter_file_splice_write().\nS:U - The corruption and crash are confined to the kernel of the affected host; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The fault is a NULL function-pointer dereference and pipe-ring state corruption; it yields no read primitive and discloses no kernel or file data to the attacker.\nI:L - ->write_iter() reports 0x7fffffffffffffff bytes written when nothing was written, so applications treat failed writes as successful (silent data loss), netfs_update_i_size() stamps a bogus/overflowed size onto the client inode, and the splice loop destroys unwritten pipe contents and leaves pipe->tail past pipe->head \u2014 limited, non-arbitrary data and metadata corruption.\nA:H - Reliable kernel NULL pointer dereference oops in iter_file_splice_write()/pipe_buf_release(), taken with the pipe mutex held, so the pipe is permanently locked and any other user of it hangs in D state; on panic_on_oops configurations it is a full system panic."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/netfs/read_collect.c", "fs/netfs/write_collect.c", "fs/netfs/write_issue.c", "fs/splice.c", "include/linux/netfs.h"], "versions": [{"version": "288ace2f57c9d06dd2e42bd80d03747d879a4068", "lessThan": "f08c80af3c9a9849cd178b4843b7c01d103506a1", "status": "affected", "versionType": "git"}, {"version": "288ace2f57c9d06dd2e42bd80d03747d879a4068", "lessThan": "387164a2b97e1f5404c6d0049a7409bac7d2bc5b", "status": "affected", "versionType": "git"}, {"version": "288ace2f57c9d06dd2e42bd80d03747d879a4068", "lessThan": "a3de58b12ce074ec05b8741fa28d62ccb1070468", "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/netfs/read_collect.c", "fs/netfs/write_collect.c", "fs/netfs/write_issue.c", "fs/splice.c", "include/linux/netfs.h"], "versions": [{"version": "6.10", "status": "affected"}, {"version": "0", "lessThan": "6.10", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.44", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.16.4", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.17", "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": "6.10", "versionEndExcluding": "6.12.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.16.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.17"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f08c80af3c9a9849cd178b4843b7c01d103506a1"}, {"url": "https://git.kernel.org/stable/c/387164a2b97e1f5404c6d0049a7409bac7d2bc5b"}, {"url": "https://git.kernel.org/stable/c/a3de58b12ce074ec05b8741fa28d62ccb1070468"}], "title": "netfs: Fix unbuffered write error handling", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/netfs/read_collect.c", "fs/netfs/write_collect.c", "fs/netfs/write_issue.c", "fs/splice.c", "include/linux/netfs.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f08c80af3c9a9849cd178b4843b7c01d103506a1", "status": "affected", "version": "288ace2f57c9d06dd2e42bd80d03747d879a4068", "versionType": "git"}, {"lessThan": "387164a2b97e1f5404c6d0049a7409bac7d2bc5b", "status": "affected", "version": "288ace2f57c9d06dd2e42bd80d03747d879a4068", "versionType": "git"}, {"lessThan": "a3de58b12ce074ec05b8741fa28d62ccb1070468", "status": "affected", "version": "288ace2f57c9d06dd2e42bd80d03747d879a4068", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/netfs/read_collect.c", "fs/netfs/write_collect.c", "fs/netfs/write_issue.c", "fs/splice.c", "include/linux/netfs.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.10"}, {"lessThan": "6.10", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.44", "versionType": "semver"}, {"lessThanOrEqual": "6.16.*", "status": "unaffected", "version": "6.16.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "6.17", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "489EF11B-3951-48B6-8DCA-E6B0DDAF7910", "versionEndExcluding": "6.12.44", "versionStartIncluding": "6.10", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "AFC28995-B8C3-4B68-8CB6-78E792B6629D", "versionEndExcluding": "6.16.4", "versionStartIncluding": "6.13", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*", "matchCriteriaId": "327D22EF-390B-454C-BD31-2ED23C998A1C", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*", "matchCriteriaId": "C730CD9A-D969-4A8E-9522-162AAF7C0EE9", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix unbuffered write error handling\n\nIf all the subrequests in an unbuffered write stream fail, the subrequest\ncollector doesn't update the stream->transferred value and it retains its\ninitial LONG_MAX value. Unfortunately, if all active streams fail, then we\ntake the smallest value of { LONG_MAX, LONG_MAX, ... } as the value to set\nin wreq->transferred - which is then returned from ->write_iter().\n\nLONG_MAX was chosen as the initial value so that all the streams can be\nquickly assessed by taking the smallest value of all stream->transferred -\nbut this only works if we've set any of them.\n\nFix this by adding a flag to indicate whether the value in\nstream->transferred is valid and checking that when we integrate the\nvalues. stream->transferred can then be initialised to zero.\n\nThis was found by running the generic/750 xfstest against cifs with\ncache=none. It splices data to the target file. Once (if) it has used up\nall the available scratch space, the writes start failing with ENOSPC.\nThis causes ->write_iter() to fail. However, it was returning\nwreq->transferred, i.e. LONG_MAX, rather than an error (because it thought\nthe amount transferred was non-zero) and iter_file_splice_write() would\nthen try to clean up that amount of pipe bufferage - leading to an oops\nwhen it overran. The kernel log showed:\n\n CIFS: VFS: Send error in write = -28\n\nfollowed by:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000008\n\nwith:\n\n RIP: 0010:iter_file_splice_write+0x3a4/0x520\n do_splice+0x197/0x4e0\n\nor:\n\n RIP: 0010:pipe_buf_release (include/linux/pipe_fs_i.h:282)\n iter_file_splice_write (fs/splice.c:755)\n\nAlso put a warning check into splice to announce if ->write_iter() returned\nthat it had written more than it was asked to."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad:\n\nnetfs: Correcci\u00f3n del manejo de errores de escritura sin b\u00fafer\n\nSi todas las subpeticiones en un flujo de escritura sin b\u00fafer fallan, el recolector de subpeticiones no actualiza el valor de stream->transferred y este retiene su valor inicial LONG_MAX. Desafortunadamente, si todos los flujos activos fallan, entonces tomamos el valor m\u00e1s peque\u00f1o de { LONG_MAX, LONG_MAX, ... } como el valor a establecer en wreq->transferred, el cual es luego devuelto desde ->write_iter().\n\nLONG_MAX fue elegido como el valor inicial para que todos los flujos puedan ser evaluados r\u00e1pidamente tomando el valor m\u00e1s peque\u00f1o de todos los stream->transferred, pero esto solo funciona si hemos establecido alguno de ellos.\n\nSolucione esto a\u00f1adiendo una bandera para indicar si el valor en stream->transferred es v\u00e1lido y verificando eso cuando integramos los valores. stream->transferred puede entonces ser inicializado a cero.\n\nEsto fue encontrado ejecutando el xfstest generic/750 contra cifs con cache=none. Empalma datos al archivo de destino. Una vez (si) ha agotado todo el espacio de trabajo disponible, las escrituras comienzan a fallar con ENOSPC. Esto causa que ->write_iter() falle. Sin embargo, estaba devolviendo wreq->transferred, es decir, LONG_MAX, en lugar de un error (porque pens\u00f3 que la cantidad transferida no era cero) e iter_file_splice_write() intentar\u00eda entonces limpiar esa cantidad de b\u00fafer de tuber\u00eda, lo que llev\u00f3 a un 'oops' cuando se desbord\u00f3. El registro del kernel mostr\u00f3:\n\n CIFS: VFS: Send error in write = -28\n\nseguido de:\n\n BUG: desreferencia de puntero NULL del kernel, direcci\u00f3n: 0000000000000008\n\ncon:\n\n RIP: 0010:iter_file_splice_write+0x3a4/0x520\n do_splice+0x197/0x4e0\n\no:\n\n RIP: 0010:pipe_buf_release (include/linux/pipe_fs_i.h:282)\n iter_file_splice_write (fs/splice.c:755)\n\nTambi\u00e9n se a\u00f1adi\u00f3 una verificaci\u00f3n de advertencia en splice para anunciar si ->write_iter() devolvi\u00f3 que hab\u00eda escrito m\u00e1s de lo que se le pidi\u00f3."}], "id": "CVE-2025-39723", "lastModified": "2026-10-19T21:10:00.160", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 4.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2025-09-05T18:15:50.043", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/387164a2b97e1f5404c6d0049a7409bac7d2bc5b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a3de58b12ce074ec05b8741fa28d62ccb1070468"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/f08c80af3c9a9849cd178b4843b7c01d103506a1"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: netfs: Fix unbuffered write error handling", "id": "2393490", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2393490"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "details": ["No description is available for this CVE."], "name": "CVE-2025-39723", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "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": "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": "2025-09-05T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-39723\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-39723\nhttps://lore.kernel.org/linux-cve-announce/2025090552-CVE-2025-39723-0daf@gregkh/T"], "threat_severity": "Moderate"}

{"created": "2025-09-06T09:01:33.235282+00:00", "updated": "2025-09-06T09:01:33.235348+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}