Skip to main content
cve.nowby Sazabi
← All vulnerabilities
CVE-2026-89711

NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

In the Linux kernel, the following vulnerability has been resolved: NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check The header for commit e75b23f9e323 ("nfsd: check d_can_lookup in fh_verify of directories") details the assumption that justified adding the WARN_ON_ONCE to nfsd_mode_check(), that assumption is invalid (in the case of NFS reexport). When NFSD exports an NFS filesystem it is very possible for nfsd_mode_check() to encounter a @dentry that doesn't have i_op->lookup (see nfs_fhget()'s NFS_ATTR_FATTR_MOUNTPOINT and NFS_ATTR_FATTR_V4_REFERRAL handling, and d_flags_for_inode()). So remove nfsd_mode_check()'s WARN_ON_ONCE(). The nfserr_notdir return on that branch must stay. It guards the subsequent lookup_one_unlocked() -> __lookup_slow() path, which calls inode->i_op->lookup() with no NULL check, so returning nfserr_notdir is what keeps a client LOOKUP into such a @dentry from dereferencing a NULL method pointer.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • Linux Linux

    From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in ae251937c6f0237e5b555a5e4ba4595b8206e865; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in e145e8d67a5d41c72d322e7f87ab474d39d9dfb7; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in 9f4434893a2783f7384d993cea883aff3fb7a52d; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in 2ef131323999539038e306773c8256403834361b; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in b55b4d880bb080fa10eb08ba21a5d8679b8102fe; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in 7ef182a8fe9c12b0d936880b1e504840639aa009; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in a275de3bac5635514ca830f2e46b5ff0e66b5c4c; From e75b23f9e323b1e0759619c39d5a9f7a3a5d9d2c · fixed in aa0cf48a448c5a9fe1a1e880899ecd589ce39e6e

  • Linux Linux

    4.8

  • KernelLinux

    From 4.8.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8

git.kernel.org