CVE-2025-39686

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It works by emulating the\n`INSN_READ` or `INSN_WRITE` instruction handling with a constructed\n`INSN_BITS` instruction. However, `INSN_READ` and `INSN_WRITE`\ninstructions are supposed to be able read or write multiple samples,\nindicated by the `insn->n` value, but `insn_rw_emulate_bits()` currently\nonly handles a single sample. For `INSN_READ`, the comedi core will\ncopy `insn->n` samples back to user-space. (That triggered KASAN\nkernel-infoleak errors when `insn->n` was greater than 1, but that is\nbeing fixed more generally elsewhere in the comedi core.)\n\nMake `insn_rw_emulate_bits()` either handle `insn->n` samples, or return\nan error, to conform to the general expectation for `INSN_READ` and\n`INSN_WRITE` handlers."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/comedi/drivers.c"], "versions": [{"version": "ed9eccbe8970f6eedc1b978c157caf1251a896d4", "lessThan": "ab77e85bd3bc006ef40738f26f446a660813da44", "status": "affected", "versionType": "git"}, {"version": "ed9eccbe8970f6eedc1b978c157caf1251a896d4", "lessThan": "ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b", "status": "affected", "versionType": "git"}, {"version": "ed9eccbe8970f6eedc1b978c157caf1251a896d4", "lessThan": "842f307a1d115b24f2bcb2415c4e344f11f55930", "status": "affected", "versionType": "git"}, {"version": "ed9eccbe8970f6eedc1b978c157caf1251a896d4", "lessThan": "92352ed2f9ac422181e381c2430c2d0dfb46faa0", "status": "affected", "versionType": "git"}, {"version": "ed9eccbe8970f6eedc1b978c157caf1251a896d4", "lessThan": "dc0a2f142d655700db43de90cb6abf141b73d908", "status": "affected", "versionType": "git"}, {"version": "ed9eccbe8970f6eedc1b978c157caf1251a896d4", "lessThan": "7afba9221f70d4cbce0f417c558879cba0eb5e66", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/comedi/drivers.c"], "versions": [{"version": "2.6.29", "status": "affected"}, {"version": "0", "lessThan": "2.6.29", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.190", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.149", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.103", "lessThanOrEqual": "6.6.*", "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": "2.6.29", "versionEndExcluding": "5.15.190"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.1.149"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.6.103"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.12.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.16.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.17"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/ab77e85bd3bc006ef40738f26f446a660813da44"}, {"url": "https://git.kernel.org/stable/c/ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b"}, {"url": "https://git.kernel.org/stable/c/842f307a1d115b24f2bcb2415c4e344f11f55930"}, {"url": "https://git.kernel.org/stable/c/92352ed2f9ac422181e381c2430c2d0dfb46faa0"}, {"url": "https://git.kernel.org/stable/c/dc0a2f142d655700db43de90cb6abf141b73d908"}, {"url": "https://git.kernel.org/stable/c/7afba9221f70d4cbce0f417c558879cba0eb5e66"}], "title": "comedi: Make insn_rw_emulate_bits() do insn->n samples", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:42:18.407Z"}}, {"x_adpType": "supplier", "providerMetadata": {"orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-05-12T12:06:13.615Z"}, "affected": [{"vendor": "Siemens", "product": "SIMATIC CN 4100", "versions": [{"status": "affected", "version": "0", "lessThan": "V5.0", "versionType": "custom"}], "defaultStatus": "unknown"}], "references": [{"url": "https://cert-portal.siemens.com/productcert/html/ssa-032379.html"}]}]}}

{}

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Similarly, it is used as a default\nhandler for `INSN_WRITE` instructions for subdevices that have a handler\nfor `INSN_BITS` but not for `INSN_WRITE`. It works by emulating the\n`INSN_READ` or `INSN_WRITE` instruction handling with a constructed\n`INSN_BITS` instruction. However, `INSN_READ` and `INSN_WRITE`\ninstructions are supposed to be able read or write multiple samples,\nindicated by the `insn->n` value, but `insn_rw_emulate_bits()` currently\nonly handles a single sample. For `INSN_READ`, the comedi core will\ncopy `insn->n` samples back to user-space. (That triggered KASAN\nkernel-infoleak errors when `insn->n` was greater than 1, but that is\nbeing fixed more generally elsewhere in the comedi core.)\n\nMake `insn_rw_emulate_bits()` either handle `insn->n` samples, or return\nan error, to conform to the general expectation for `INSN_READ` and\n`INSN_WRITE` handlers."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ncomedi: Hacer que 'insn_rw_emulate_bits()' procese 'insn->n' muestras\n\nLa funci\u00f3n 'insn_rw_emulate_bits()' se utiliza como gestor predeterminado para instrucciones 'INSN_READ' para subdispositivos que tienen un gestor para 'INSN_BITS' pero no para 'INSN_READ'. De manera similar, se utiliza como gestor predeterminado para instrucciones 'INSN_WRITE' para subdispositivos que tienen un gestor para 'INSN_BITS' pero no para 'INSN_WRITE'. Funciona emulando el manejo de instrucciones 'INSN_READ' o 'INSN_WRITE' con una instrucci\u00f3n 'INSN_BITS' construida. Sin embargo, las instrucciones 'INSN_READ' e 'INSN_WRITE' deber\u00edan poder leer o escribir m\u00faltiples muestras, indicado por el valor 'insn->n', pero 'insn_rw_emulate_bits()' actualmente solo maneja una \u00fanica muestra. Para 'INSN_READ', el n\u00facleo de comedi copiar\u00e1 'insn->n' muestras de vuelta al espacio de usuario. (Eso desencaden\u00f3 errores de fuga de informaci\u00f3n del kernel de KASAN cuando 'insn->n' era mayor que 1, pero eso se est\u00e1 corrigiendo de manera m\u00e1s general en otra parte del n\u00facleo de comedi.)\n\nHacer que 'insn_rw_emulate_bits()' maneje 'insn->n' muestras, o devuelva un error, para ajustarse a la expectativa general para los gestores de 'INSN_READ' e 'INSN_WRITE'."}], "id": "CVE-2025-39686", "lastModified": "2026-10-19T21:10:00.160", "metrics": {"cvssMetricV31": [{"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": "2025-09-05T18:15:45.297", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/7afba9221f70d4cbce0f417c558879cba0eb5e66"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/842f307a1d115b24f2bcb2415c4e344f11f55930"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/92352ed2f9ac422181e381c2430c2d0dfb46faa0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ab77e85bd3bc006ef40738f26f446a660813da44"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/dc0a2f142d655700db43de90cb6abf141b73d908"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"], "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}, {"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "url": "https://cert-portal.siemens.com/productcert/html/ssa-032379.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: comedi: Make insn_rw_emulate_bits() do insn->n samples", "id": "2393487", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2393487"}, "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"}, "details": ["No description is available for this CVE."], "name": "CVE-2025-39686", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "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": "2025-09-05T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-39686\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-39686\nhttps://lore.kernel.org/linux-cve-announce/2025090546-CVE-2025-39686-afb8@gregkh/T"], "threat_severity": "Moderate"}

{"created": "2025-09-06T09:01:39.416137+00:00", "updated": "2025-09-06T09:01:39.416184+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}