{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31402","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-03-09T15:48:24.086Z","datePublished":"2026-04-03T15:16:05.724Z","dateUpdated":"2026-04-27T14:02:49.450Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-04-27T14:02:49.450Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix heap overflow in NFSv4.0 LOCK replay cache\n\nThe NFSv4.0 replay cache uses a fixed 112-byte inline buffer\n(rp_ibuf[NFSD4_REPLAY_ISIZE]) to store encoded operation responses.\nThis size was calculated based on OPEN responses and does not account\nfor LOCK denied responses, which include the conflicting lock owner as\na variable-length field up to 1024 bytes (NFS4_OPAQUE_LIMIT).\n\nWhen a LOCK operation is denied due to a conflict with an existing lock\nthat has a large owner, nfsd4_encode_operation() copies the full encoded\nresponse into the undersized replay buffer via read_bytes_from_xdr_buf()\nwith no bounds check. This results in a slab-out-of-bounds write of up\nto 944 bytes past the end of the buffer, corrupting adjacent heap memory.\n\nThis can be triggered remotely by an unauthenticated attacker with two\ncooperating NFSv4.0 clients: one sets a lock with a large owner string,\nthen the other requests a conflicting lock to provoke the denial.\n\nWe could fix this by increasing NFSD4_REPLAY_ISIZE to allow for a full\nopaque, but that would increase the size of every stateowner, when most\nlockowners are not that large.\n\nInstead, fix this by checking the encoded response length against\nNFSD4_REPLAY_ISIZE before copying into the replay buffer. If the\nresponse is too large, set rp_buflen to 0 to skip caching the replay\npayload. The status is still cached, and the client already received the\ncorrect response on the original request."}],"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"}}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4xdr.c","fs/nfsd/state.h"],"versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"f9fcb4441f6c02bb20c2eb340101e27dfe23607c","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"c9452c0797c95cf2378170df96cf4f4b3bca7eff","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"8afb437ea1f70cacb4bbdf11771fb5c4d720b965","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"0f0e2a54a31a7f9ad2915db99156114872317388","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"ae8498337dfdfda71bdd0b807c9a23a126011d76","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"5133b61aaf437e5f25b1b396b14242a6bb0508e2","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4xdr.c","fs/nfsd/state.h"],"versions":[{"version":"2.6.12","status":"affected"},{"version":"0","lessThan":"2.6.12","status":"unaffected","versionType":"semver"},{"version":"5.10.253","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"6.1.167","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.130","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.78","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.20","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"6.19.10","lessThanOrEqual":"6.19.*","status":"unaffected","versionType":"semver"},{"version":"7.0","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":"2.6.12","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.167"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.20"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.19.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.0"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/f9fcb4441f6c02bb20c2eb340101e27dfe23607c"},{"url":"https://git.kernel.org/stable/c/c9452c0797c95cf2378170df96cf4f4b3bca7eff"},{"url":"https://git.kernel.org/stable/c/8afb437ea1f70cacb4bbdf11771fb5c4d720b965"},{"url":"https://git.kernel.org/stable/c/dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0"},{"url":"https://git.kernel.org/stable/c/0f0e2a54a31a7f9ad2915db99156114872317388"},{"url":"https://git.kernel.org/stable/c/ae8498337dfdfda71bdd0b807c9a23a126011d76"},{"url":"https://git.kernel.org/stable/c/5133b61aaf437e5f25b1b396b14242a6bb0508e2"}],"title":"nfsd: fix heap overflow in NFSv4.0 LOCK replay cache","x_generator":{"engine":"bippy-1.2.0"}}}}