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CVE-2026-31403

NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.20, and 1 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in 76740c28050dc6db2f5550f1325b00a11bbb3255; From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in c7f406fb341d6747634b8b1fa5461656e5e56076; From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in d1a19217995df9c7e4118f5a2820c5032fef2945; From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in e3d77f935639e6ae4b381c80464c31df998d61f4; From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6; From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in 6a8d70e2ad6aad2c345a5048edcb8168036f97d6; From 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 · fixed in e7fcf179b82d3a3730fd8615da01b087cc654d0b

  • Linux Linux

    3.9

  • KernelLinux

    From 3.9.0 · fixed in 5.10.253; From 5.11.0 · fixed in 6.1.167; From 6.2.0 · fixed in 6.6.130; From 6.7.0 · fixed in 6.12.78; From 6.13.0 · fixed in 6.18.20; From 6.19.0 · fixed in 6.19.10

References 7

git.kernel.org