{"id":"CVE-2026-89699","state":"PUBLISHED","title":"nfsd: validate symlink target length in NFSv4 CREATE","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: validate symlink target length in NFSv4 CREATE\n\nnfsd4_decode_create() accepts an unbounded cr_datalen from the wire for\nNF4LNK symlink targets, allowing a client to force a kmalloc of up to\nthe maximum RPC payload size (several MiB) per COMPOUND op that persists\nuntil compound teardown.  The VFS rejects oversized targets with\nENAMETOOLONG, but the allocation has already occurred.\n\nReject cr_datalen == 0 early with nfserr_inval and cr_datalen greater\nthan NFS4_MAXPATHLEN (PATH_MAX) with nfserr_nametoolong to bound the\nallocation.","publishedAt":"2026-09-11T19:46:17.293Z","updatedAt":"2026-10-19T08:51:12.396Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"36011308b3f01ce7dc9954f3cefcbb5291af9f95","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"888dad4b557352cf85be31613407b5ba51ad07d1","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"8661d3cb38fd148947e57dbc0871fd4d3fa33bbf","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3ef5e7a01a4d74995a65496bc9166d1e980a4355","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b24843ea3de1676b29902457b38507c95a80649b","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"895a485cd3758031ef9993c0d53cf19ce8fb4ccc","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"45ec115cbfecb4b3cfab7fca6f73d1b60696a25a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"041f57056e5fb9c80adc088269322d2c61074406","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4xdr.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4xdr.c"]}],"references":["https://git.kernel.org/stable/c/36011308b3f01ce7dc9954f3cefcbb5291af9f95","https://git.kernel.org/stable/c/888dad4b557352cf85be31613407b5ba51ad07d1","https://git.kernel.org/stable/c/8661d3cb38fd148947e57dbc0871fd4d3fa33bbf","https://git.kernel.org/stable/c/3ef5e7a01a4d74995a65496bc9166d1e980a4355","https://git.kernel.org/stable/c/b24843ea3de1676b29902457b38507c95a80649b","https://git.kernel.org/stable/c/895a485cd3758031ef9993c0d53cf19ce8fb4ccc","https://git.kernel.org/stable/c/45ec115cbfecb4b3cfab7fca6f73d1b60696a25a","https://git.kernel.org/stable/c/041f57056e5fb9c80adc088269322d2c61074406"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89699.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89699","state":"PUBLISHED","datePublished":"2026-09-11T19:46:17.293Z","dateUpdated":"2026-10-19T08:51:12.396Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.750Z"},"containers":{"cna":{"title":"nfsd: validate symlink target length in NFSv4 CREATE","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: validate symlink target length in NFSv4 CREATE\n\nnfsd4_decode_create() accepts an unbounded cr_datalen from the wire for\nNF4LNK symlink targets, allowing a client to force a kmalloc of up to\nthe maximum RPC payload size (several MiB) per COMPOUND op that persists\nuntil compound teardown.  The VFS rejects oversized targets with\nENAMETOOLONG, but the allocation has already occurred.\n\nReject cr_datalen == 0 early with nfserr_inval and cr_datalen greater\nthan NFS4_MAXPATHLEN (PATH_MAX) with nfserr_nametoolong to bound the\nallocation."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"36011308b3f01ce7dc9954f3cefcbb5291af9f95","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"888dad4b557352cf85be31613407b5ba51ad07d1","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"8661d3cb38fd148947e57dbc0871fd4d3fa33bbf","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3ef5e7a01a4d74995a65496bc9166d1e980a4355","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b24843ea3de1676b29902457b38507c95a80649b","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"895a485cd3758031ef9993c0d53cf19ce8fb4ccc","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"45ec115cbfecb4b3cfab7fca6f73d1b60696a25a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"041f57056e5fb9c80adc088269322d2c61074406","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4xdr.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4xdr.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/36011308b3f01ce7dc9954f3cefcbb5291af9f95"},{"url":"https://git.kernel.org/stable/c/888dad4b557352cf85be31613407b5ba51ad07d1"},{"url":"https://git.kernel.org/stable/c/8661d3cb38fd148947e57dbc0871fd4d3fa33bbf"},{"url":"https://git.kernel.org/stable/c/3ef5e7a01a4d74995a65496bc9166d1e980a4355"},{"url":"https://git.kernel.org/stable/c/b24843ea3de1676b29902457b38507c95a80649b"},{"url":"https://git.kernel.org/stable/c/895a485cd3758031ef9993c0d53cf19ce8fb4ccc"},{"url":"https://git.kernel.org/stable/c/45ec115cbfecb4b3cfab7fca6f73d1b60696a25a"},{"url":"https://git.kernel.org/stable/c/041f57056e5fb9c80adc088269322d2c61074406"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The flaw is reached through the in-kernel NFS server (nfsd) when a remote client sends an NFSv4 COMPOUND containing OP_CREATE of type NF4LNK over TCP/UDP port 2049; nfsd4_decode_create() runs during XDR decode of that compound.\nAC:L - A client fully controls cr_datalen on the wire; one COMPOUND with an NF4LNK target larger than PATH_MAX but within the RPC payload deterministically forces svcxdr_dupstr()/kmalloc of that size, with no race or attacker-uncontrollable condition.\nPR:N - The oversized kmalloc occurs in nfsd4_decode_compound() before SEQUENCE/session checks, PUTFH, fh_verify(), or export flavor enforcement; AUTH_NULL and AUTH_UNIX are accepted at the RPC layer, so an unauthenticated peer that can reach nfsd needs no host credentials.\nUI:N - Exploitation requires only attacker-sent NFSv4 COMPOUND RPCs; no administrator or end-user action on the server is needed beyond nfsd already listening.\nS:U - Impact is confined to kernel memory consumption on the NFS server within the same security authority; there is no VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:N - The defect only copies attacker-supplied symlink-target bytes into a correctly sized kmalloc buffer; there is no out-of-bounds read, use-after-free, or other disclosure primitive.\nI:N - There is no memory corruption or attacker-controlled write; the buffer is sized to cr_datalen and is only a temporary copy that filesystems later reject with ENAMETOOLONG.\nA:H - Each COMPOUND can force a GFP_KERNEL kmalloc of up to the maximum RPC payload (several MiB) on an nfsd thread until compound teardown; flooding concurrent requests across nfsd threads can exhaust kernel memory and OOM or stall the host."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:51:12.396Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-89699","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T19:26:10.914842Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:26:49.108Z"}}]}}}