{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-37879", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.962Z", "datePublished": "2025-05-09T06:45:43.197Z", "dateUpdated": "2026-08-05T11:58:00.365Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:58:00.365Z" }, "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)" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The attacker is the remote 9p file server, reachable over the TCP transport (`p9_fd_create_tcp`, port 564) or RDMA; 9p is unauthenticated and unencrypted on the wire, so a malicious server or an on-path MITM can inject the bogus RWRITE reply. 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 — 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" } } ] } }