CVE-2026-31403 (GCVE-0-2026-31403)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:16 – Updated: 2026-04-03 15:16
VLAI?
Title
NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd
Summary
In the Linux kernel, the following vulnerability has been resolved: NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd The /proc/fs/nfs/exports proc entry is created at module init and persists for the module's lifetime. exports_proc_open() captures the caller's current network namespace and stores its svc_export_cache in seq->private, but takes no reference on the namespace. If the namespace is subsequently torn down (e.g. container destruction after the opener does setns() to a different namespace), nfsd_net_exit() calls nfsd_export_shutdown() which frees the cache. Subsequent reads on the still-open fd dereference the freed cache_detail, walking a freed hash table. Hold a reference on the struct net for the lifetime of the open file descriptor. This prevents nfsd_net_exit() from running -- and thus prevents nfsd_export_shutdown() from freeing the cache -- while any exports fd is open. cache_detail already stores its net pointer (cd->net, set by cache_create_net()), so exports_release() can retrieve it without additional per-file storage.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 , < c7f406fb341d6747634b8b1fa5461656e5e56076 (git)
Affected: 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 , < d1a19217995df9c7e4118f5a2820c5032fef2945 (git)
Affected: 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 , < e3d77f935639e6ae4b381c80464c31df998d61f4 (git)
Affected: 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 , < db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6 (git)
Affected: 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 , < 6a8d70e2ad6aad2c345a5048edcb8168036f97d6 (git)
Affected: 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 , < e7fcf179b82d3a3730fd8615da01b087cc654d0b (git)
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    Linux Linux Affected: 3.9
Unaffected: 0 , < 3.9 (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc5 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd\n\nThe /proc/fs/nfs/exports proc entry is created at module init\nand persists for the module\u0027s lifetime. exports_proc_open()\ncaptures the caller\u0027s current network namespace and stores\nits svc_export_cache in seq-\u003eprivate, but takes no reference\non the namespace. If the namespace is subsequently torn down\n(e.g. container destruction after the opener does setns() to a\ndifferent namespace), nfsd_net_exit() calls nfsd_export_shutdown()\nwhich frees the cache. Subsequent reads on the still-open fd\ndereference the freed cache_detail, walking a freed hash table.\n\nHold a reference on the struct net for the lifetime of the open\nfile descriptor. This prevents nfsd_net_exit() from running --\nand thus prevents nfsd_export_shutdown() from freeing the cache\n-- while any exports fd is open. cache_detail already stores\nits net pointer (cd-\u003enet, set by cache_create_net()), so\nexports_release() can retrieve it without additional per-file\nstorage."
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}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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