CVE-2025-37879

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The same primitive is available to a malicious hypervisor backend over virtio/Xen.\nAC:L - The server simply answers any TWRITE with a success reply carrying count 0xFFFFFFFF, deterministically bypassing the signed `rsize < written` check. There is no race, no timing window, and no dependence on memory layout to reach the corruption.\nPR:N - The malicious 9p server is a remote peer holding no credentials or account on the victim client; 9p mounts commonly use auth=none, and an on-path attacker needs nothing at all. The mount being present is an environmental precondition, not a privilege held by the attacker.\nUI:N - On an already-mounted 9p share the bug fires on ordinary I/O, including kernel-initiated page-cache writeback via `v9fs_issue_write`, with no victim action required. No specific human interaction beyond the pre-existing mount configuration is needed.\nS:U - The corruption is confined to the 9p client kernel that parsed the reply, with no crossing into a different security authority such as a hypervisor or IOMMU boundary. Impact stays within the victim kernel's own scope.\nC:H - The over-revert leaves `i->bvec`/`i->__iov` pointing before the start of the bio_vec/kvec array, and because `p9_client_write()` keeps looping the next TWRITE marshals data from that out-of-bounds descriptor \u2014 sending adjacent kernel heap or stack memory straight to the attacker-controlled server. This is a repeatable kernel memory disclosure primitive.\nI:H - The same out-of-bounds iterator descriptor supplies attacker-uncontrolled `bv_page`/`iov_base` pointers used for subsequent copies, giving out-of-bounds kernel memory access leveragable for control-flow hijack. Additionally `offset += written` sign-extends the negative count into the u64 file offset and `total` goes negative, corrupting file data placement and netfs transfer accounting.\nA:H - The reported and reproduced result is a NULL pointer dereference in `iov_iter_folioq_revert()` when `folioq->prev` is NULL at the queue head, and `ITER_UBUF`/`ITER_XARRAY` hit an explicit `BUG()` in `iov_iter_revert()`. The write loop also never terminates because `i->count` grows by one each iteration, hanging the task."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/9p/client.c"], "versions": [{"version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "lessThan": "468ff4a7c61fb811c596a7c44b6a5455e40fd12b", "status": "affected", "versionType": "git"}, {"version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "lessThan": "a68768e280b7d0c967ea509e791bb9b90adc94a5", "status": "affected", "versionType": "git"}, {"version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "lessThan": "c548f95688e2b5ae0e2ae43d53cf717156c7d034", "status": "affected", "versionType": "git"}, {"version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "lessThan": "374e4cd75617c8c2552f562f39dd989583f5c330", "status": "affected", "versionType": "git"}, {"version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "lessThan": "d0259a856afca31d699b706ed5e2adf11086c73b", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/9p/client.c"], "versions": [{"version": "4.1", "status": "affected"}, {"version": "0", "lessThan": "4.1", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.136", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.89", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.26", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.14.5", "lessThanOrEqual": "6.14.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.15", "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": "4.1", "versionEndExcluding": "6.1.136"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.6.89"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.12.26"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.14.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.15"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/468ff4a7c61fb811c596a7c44b6a5455e40fd12b"}, {"url": "https://git.kernel.org/stable/c/a68768e280b7d0c967ea509e791bb9b90adc94a5"}, {"url": "https://git.kernel.org/stable/c/c548f95688e2b5ae0e2ae43d53cf717156c7d034"}, {"url": "https://git.kernel.org/stable/c/374e4cd75617c8c2552f562f39dd989583f5c330"}, {"url": "https://git.kernel.org/stable/c/d0259a856afca31d699b706ed5e2adf11086c73b"}], "title": "9p/net: fix improper handling of bogus negative read/write replies", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:56:51.125Z"}}]}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/9p/client.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "468ff4a7c61fb811c596a7c44b6a5455e40fd12b", "status": "affected", "version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "versionType": "git"}, {"lessThan": "a68768e280b7d0c967ea509e791bb9b90adc94a5", "status": "affected", "version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "versionType": "git"}, {"lessThan": "c548f95688e2b5ae0e2ae43d53cf717156c7d034", "status": "affected", "version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "versionType": "git"}, {"lessThan": "374e4cd75617c8c2552f562f39dd989583f5c330", "status": "affected", "version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "versionType": "git"}, {"lessThan": "d0259a856afca31d699b706ed5e2adf11086c73b", "status": "affected", "version": "070b3656cf228eaaef7b28b59264c5c7cdbdd0fb", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/9p/client.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.1"}, {"lessThan": "4.1", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.136", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.89", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.26", "versionType": "semver"}, {"lessThanOrEqual": "6.14.*", "status": "unaffected", "version": "6.14.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "6.15", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "05A05DE3-3248-434C-8967-0FB26A540FA5", "versionEndExcluding": "6.1.136", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "D79CE030-3114-45E0-B52B-C77781BCB587", "versionEndExcluding": "6.6.89", "versionStartIncluding": "6.2", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "22F52099-F422-4D19-8283-45F9F9BF4392", "versionEndExcluding": "6.12.26", "versionStartIncluding": "6.7", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "6B25CA7E-4CD0-46DB-B4EF-13A3516071FB", "versionEndExcluding": "6.14.5", "versionStartIncluding": "6.13", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*", "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\n9p/net: fix improper handling of bogus negative read/write replies\n\nIn p9_client_write() and p9_client_read_once(), if the server\nincorrectly replies with success but a negative write/read count then we\nwould consider written (negative) <= rsize (positive) because both\nvariables were signed.\n\nMake variables unsigned to avoid this problem.\n\nThe reproducer linked below now fails with the following error instead\nof a null pointer deref:\n9pnet: bogus RWRITE count (4294967295 > 3)"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: 9p/net: se corrige el manejo incorrecto de respuestas de lectura/escritura negativas falsas. En p9_client_write() y p9_client_read_once(), si el servidor responde incorrectamente con \u00e9xito, pero con un recuento de escrituras/lecturas negativo, se considerar\u00eda que \"escrito\" (negativo) &lt;= \"rsize\" (positivo) porque ambas variables estaban firmadas. Para evitar este problema, desactive el signo de las variables. El reproductor enlazado a continuaci\u00f3n ahora falla con el siguiente error en lugar de una referencia de puntero nulo: 9pnet: recuento de RWRITE falso (4294967295 &gt; 3)"}], "id": "CVE-2025-37879", "lastModified": "2026-07-30T06:22:27.160", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.2, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2025-05-09T07:16:09.143", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/374e4cd75617c8c2552f562f39dd989583f5c330"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/468ff4a7c61fb811c596a7c44b6a5455e40fd12b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a68768e280b7d0c967ea509e791bb9b90adc94a5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c548f95688e2b5ae0e2ae43d53cf717156c7d034"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/d0259a856afca31d699b706ed5e2adf11086c73b"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"], "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-125"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: 9p/net: fix improper handling of bogus negative read/write replies", "id": "2365241", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2365241"}, "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": ["In the Linux kernel, the following vulnerability has been resolved:\n9p/net: fix improper handling of bogus negative read/write replies\nIn p9_client_write() and p9_client_read_once(), if the server\nincorrectly replies with success but a negative write/read count then we\nwould consider written (negative) <= rsize (positive) because both\nvariables were signed.\nMake variables unsigned to avoid this problem.\nThe reproducer linked below now fails with the following error instead\nof a null pointer deref:\n9pnet: bogus RWRITE count (4294967295 > 3)"], "name": "CVE-2025-37879", "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": "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": "2025-05-09T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-37879\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-37879\nhttps://lore.kernel.org/linux-cve-announce/2025050943-CVE-2025-37879-a59f@gregkh/T"], "threat_severity": "Moderate"}

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