{"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"}}]}}