CVE-2026-45983

NFSv4 session interruption via deferred idmap lookup

Published May 27, 2026 · Updated May 27, 2026

Denial of service in Linux kernel NFSD allows local users to interrupt NFSv4 sessions through delayed idmap lookup replies. During compound decoding, cache_check marks the request for deferral and drops it before nfs4svc_encode_compoundres clears NFSD4_SLOT_INUSE. Reachability requires NFSDv4 and an operation such as SETATTR whose idmap reply exceeds the timeout; later requests using the occupied session slot fail with NFSERR_JUKEBOX.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux kernel NFSD allows local users to interrupt NFSv4 sessions through delayed idmap lookup replies. During compound decoding, cache_check marks the request for deferral and drops it before nfs4svc_encode_compoundres clears NFSD4_SLOT_INUSE. Reachability requires NFSDv4 and an operation such as SETATTR whose idmap reply exceeds the timeout; later requests using the occupied session slot fail with NFSERR_JUKEBOX.

The record

CVE
CVE-2026-45983
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.30
  2. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <063a6f22478ef929625000a2caf54667725c1dfd
  3. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <243f71ed873ff3feeb6f9b5cb145d63f7188b4c4
  4. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <3a72c7dedc99b321e0f267e4e999e5baf07c4593
  5. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <8dff54fe88c0dcd4c55bff9fc2fa6ca968290826
  6. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <99e17b20fddac19a228d213e00f6b9e1c10daff9
  7. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <b9abb760db20504240a7147f27934d900cd80b23
  8. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <d75ec4504a4340b033b15cad0303988b3089dd93
  9. Affected versionversion=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <f9c206cdc4266caad6a9a7f46341420a10f03ccb

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.30; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <063a6f22478ef929625000a2caf54667725c1dfd; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <243f71ed873ff3feeb6f9b5cb145d63f7188b4c4; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <3a72c7dedc99b321e0f267e4e999e5baf07c4593; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <8dff54fe88c0dcd4c55bff9fc2fa6ca968290826; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <99e17b20fddac19a228d213e00f6b9e1c10daff9; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <b9abb760db20504240a7147f27934d900cd80b23; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <d75ec4504a4340b033b15cad0303988b3089dd93; version=2f425878b6a71571341dcd3f9e9d1a6f6355da9c <f9c206cdc4266caad6a9a7f46341420a10f03ccb

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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