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Fencer Vulns
medium 5.5

CVE-2026-45983 json

nfsd: never defer requests during idmap lookup

published 2026-05-27 5 mo ago modified 2026-11-06 2 d ago also EUVD-2026-32268

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4, 7.0
  • linux Debian 12 6.1.170-1
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.18.14-1

debian advisories DEBIAN-CVE-2026-45983

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-134.134
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1060.63
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1063.69
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1108.114
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1058.64

ubuntu advisories UBUNTU-CVE-2026-45983

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1
  • kernel-obs-build Linux Micro Extras 6.2 6.12.0-160000.36.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.36.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.36.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1.160000.2.17
  • kernel-azure SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.36.1

suse advisories SUSE-SU-2026:22742-1SUSE-SU-2026:22769-1SUSE-SU-2026:22835-1SUSE-SU-2026:22812-1SUSE-SU-2026:22433-1SUSE-SU-2026:22458-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.36.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.36.1

opensuse advisories openSUSE-SU-2026:21388-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-45983 updated cvss 7.0

kernel: nfsd: never defer requests during idmap lookup

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 d ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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