CVE-2026-45983
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
A vulnerability has been identified in the Linux kernel related to NFSv4 request handling. Delays in idmap upcall responses can lead to request rejections, resulting in client session errors.
Risk Assessment
Organizations using NFSv4 may experience session handling issues, leading to communication errors with clients and potential service downtime.
Recommendation
It is recommended to update the Linux kernel to the latest version to eliminate this vulnerability and ensure proper NFSv4 request handling.
Original NVD description (English source)
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.