{"id":"CVE-2026-53026","state":"PUBLISHED","title":"NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg\n\nIn nfsd4_add_rdaccess_to_wrdeleg, if fp->fi_fds[O_RDONLY] is already\nset by another thread, __nfs4_file_get_access should not be called\nto increment the nfs4_file access count since that was already done\nby the thread that added READ access to the file. The extra fi_access\ncount in nfs4_file can prevent the corresponding nfsd_file from being\nfreed.\n\nWhen stopping nfs-server service, these extra access counts trigger a\nBUG in kmem_cache_destroy() that shows nfsd_file object remaining on\n__kmem_cache_shutdown.\n\nThis problem can be reproduced by running the Git project's test\nsuite over NFS.","publishedAt":"2026-06-24T16:29:34.855Z","updatedAt":"2026-08-05T12:32:44.026Z","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":"c07dc84ed67c5a182273171639bacbbb87c12175","status":"affected","lessThan":"4584229395d0d65bd517780afe97ffea07cb2c3d","versionType":"git"},{"version":"8072e34e1387d03102b788677d491e2bcceef6f5","status":"affected","lessThan":"b81572b073441dfd32213e41857676d0dbff4665","versionType":"git"},{"version":"8072e34e1387d03102b788677d491e2bcceef6f5","status":"affected","lessThan":"b48f44f36e6607b2f818560f19deb86b4a9c717b","versionType":"git"},{"version":"6.18.4","status":"affected","lessThan":"6.18.33","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.19","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]}],"references":["https://git.kernel.org/stable/c/4584229395d0d65bd517780afe97ffea07cb2c3d","https://git.kernel.org/stable/c/b81572b073441dfd32213e41857676d0dbff4665","https://git.kernel.org/stable/c/b48f44f36e6607b2f818560f19deb86b4a9c717b"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53026.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53026","state":"PUBLISHED","datePublished":"2026-06-24T16:29:34.855Z","dateUpdated":"2026-08-05T12:32:44.026Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.379Z"},"containers":{"cna":{"title":"NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg\n\nIn nfsd4_add_rdaccess_to_wrdeleg, if fp->fi_fds[O_RDONLY] is already\nset by another thread, __nfs4_file_get_access should not be called\nto increment the nfs4_file access count since that was already done\nby the thread that added READ access to the file. The extra fi_access\ncount in nfs4_file can prevent the corresponding nfsd_file from being\nfreed.\n\nWhen stopping nfs-server service, these extra access counts trigger a\nBUG in kmem_cache_destroy() that shows nfsd_file object remaining on\n__kmem_cache_shutdown.\n\nThis problem can be reproduced by running the Git project's test\nsuite over NFS."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c07dc84ed67c5a182273171639bacbbb87c12175","status":"affected","lessThan":"4584229395d0d65bd517780afe97ffea07cb2c3d","versionType":"git"},{"version":"8072e34e1387d03102b788677d491e2bcceef6f5","status":"affected","lessThan":"b81572b073441dfd32213e41857676d0dbff4665","versionType":"git"},{"version":"8072e34e1387d03102b788677d491e2bcceef6f5","status":"affected","lessThan":"b48f44f36e6607b2f818560f19deb86b4a9c717b","versionType":"git"},{"version":"6.18.4","status":"affected","lessThan":"6.18.33","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.19","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4584229395d0d65bd517780afe97ffea07cb2c3d"},{"url":"https://git.kernel.org/stable/c/b81572b073441dfd32213e41857676d0dbff4665"},{"url":"https://git.kernel.org/stable/c/b48f44f36e6607b2f818560f19deb86b4a9c717b"}],"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 - NFSD is a network-facing NFS server subsystem, and the vulnerable path is reached by remote NFSv4 COMPOUND/OPEN requests over RPC.\nAC:L - A client can drive repeated or concurrent OPEN/write-delegation activity against an exported file; the relevant race/refcount condition is controllable by issuing parallel NFS requests.\nPR:N - In a reasonable NFS deployment using AUTH_SYS/AUTH_NULL-accessible exports, a remote client can reach this path without authenticated target-system privileges.\nUI:N - No victim user action is required; the attacker only sends NFS requests to the server.\nS:U - The impact remains within the vulnerable kernel/NFSD server security authority and does not cross a VM, sandbox, or other separate security boundary.\nC:N - The bug is an extra reference/access count leak, not a use-after-free, out-of-bounds access, or information disclosure primitive.\nI:N - The investigation found no attacker-controlled memory overwrite or data modification primitive; the corruption is limited to over-retaining an internal reference count.\nA:H - The leaked access counts can keep nfsd_file objects pinned and trigger a kmem_cache_destroy BUG during NFSD shutdown; repeated triggering can deny service through persistent kernel resource leakage."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:32:44.026Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18.4","versionEndExcluding":"6.18.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}