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CVE PROGRAM SOURCE RECORD7.5 High

CVE-2026-90234

NFS: Return a delegation the client fails to record

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: NFS: Return a delegation the client fails to record When an NFS server grants a delegation in an OPEN reply, nfs_inode_set_delegation() records it on the client. However, three of its error flows return without sending DELEGRETURN. A delegation can be relinquished only by DELEGRETURN (RFC 8881 Section 20.2.4), so dropping one silently leaves the server believing the client still holds it. If the server happens to recall that delegation, the client answers CB_RECALL with NFS4ERR_BADHANDLE because it has no record of the stateid. The server revokes the delegation and moves it onto its cl_revoked list, because the client never sends the FREE_STATEID that would drain it. Every subsequent SEQUENCE reply then carries SEQ4_STATUS_RECALLABLE_STATE_REVOKED, and the client's state manager loops issuing TEST_STATEID across its delegations without ever clearing the condition. The window is easy to reach now that a server offers a write delegation on any write OPEN: a delegation recalled for one opener races a re-open that the server answers with a fresh write delegation. Instead of dropping it, hand the delegation back during these error flows.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • ade04647dd56881e285983af3db702d56ee97e86 to < 61b23f482b2082e77d2f78bd1624f93a12ec35ceaffected
  • ade04647dd56881e285983af3db702d56ee97e86 to < 9e71e332fa2c7a48f3d00001f856a13cc2d69639affected
  • ade04647dd56881e285983af3db702d56ee97e86 to < fe3b1c8966a27b70599d28ce7e80819adac1ff22affected
  • ade04647dd56881e285983af3db702d56ee97e86 to < 6822ba1ae9b6df6a094f7f8998f1da734c85fa19affected
  • ade04647dd56881e285983af3db702d56ee97e86 to < 92533e49fe3c455088657b862cf3562260c0ce25affected
  • ade04647dd56881e285983af3db702d56ee97e86 to < 220af23d863995091f0edeb1e6aa0945b3db8b37affected

Linux Linux

Default version status: affected

  • 4.0affected
  • 0 to < 4.0unaffected
  • 6.1.191 to ≤ 6.1.*unaffected
  • 6.6.160 to ≤ 6.6.*unaffected
  • 6.12.114 to ≤ 6.12.*unaffected
  • 6.18.57 to ≤ 6.18.*unaffected
  • 7.2.6 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References