CVE-2026-45983
nfsd: never defer requests during idmap lookup
Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: never defer requests during idmap lookup During v4 request compound arg decoding, some ops (e.g. SETATTR) can trigger idmap lookup upcalls. When those upcall responses get delayed beyond the allowed time limit, cache_check() will mark the request for deferral and cause it to be dropped. This prevents nfs4svc_encode_compoundres from being executed, and thus the session slot flag NFSD4_SLOT_INUSE never gets cleared. Subsequent client requests will fail with NFSERR_JUKEBOX, given that the slot will be marked as in-use, making the SEQUENCE op fail. Fix this by making sure that the RQ_USEDEFERRAL flag is always clear during nfs4svc_decode_compoundargs(), since no v4 request should ever be deferred.
INFO
Published Date :
May 27, 2026, 2:17 p.m.
Last Modified :
May 27, 2026, 2:48 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Modify nfsd to clear RQ_USEDEFERRAL during compound argument decoding.
- Ensure no v4 requests are deferred.
- Prevent NFSERR_JUKEBOX errors.
- Apply the kernel patch.
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
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approaches employed by adversaries to exploit the CVE-2026-45983
weaknesses.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 27, 2026
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: nfsd: never defer requests during idmap lookup During v4 request compound arg decoding, some ops (e.g. SETATTR) can trigger idmap lookup upcalls. When those upcall responses get delayed beyond the allowed time limit, cache_check() will mark the request for deferral and cause it to be dropped. This prevents nfs4svc_encode_compoundres from being executed, and thus the session slot flag NFSD4_SLOT_INUSE never gets cleared. Subsequent client requests will fail with NFSERR_JUKEBOX, given that the slot will be marked as in-use, making the SEQUENCE op fail. Fix this by making sure that the RQ_USEDEFERRAL flag is always clear during nfs4svc_decode_compoundargs(), since no v4 request should ever be deferred. Added Reference https://git.kernel.org/stable/c/063a6f22478ef929625000a2caf54667725c1dfd Added Reference https://git.kernel.org/stable/c/243f71ed873ff3feeb6f9b5cb145d63f7188b4c4 Added Reference https://git.kernel.org/stable/c/3a72c7dedc99b321e0f267e4e999e5baf07c4593 Added Reference https://git.kernel.org/stable/c/8dff54fe88c0dcd4c55bff9fc2fa6ca968290826 Added Reference https://git.kernel.org/stable/c/99e17b20fddac19a228d213e00f6b9e1c10daff9 Added Reference https://git.kernel.org/stable/c/b9abb760db20504240a7147f27934d900cd80b23 Added Reference https://git.kernel.org/stable/c/d75ec4504a4340b033b15cad0303988b3089dd93 Added Reference https://git.kernel.org/stable/c/f9c206cdc4266caad6a9a7f46341420a10f03ccb