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NVD / CVE Program· CNA Linux

CVE-2026-45983: nfsd: never defer requests during idmap lookup

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 063a6f22478ef929625000a2caf54667725c1dfd, 243f71ed873ff3feeb6f9b5cb145d63f7188b4c4, 3a72c7dedc99b321e0f267e4e999e5baf07c4593.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 063a6f22478ef929625000a2caf54667725c1dfd, 243f71ed873ff3feeb6f9b5cb145d63f7188b4c4, 3a72c7dedc99b321e0f267e4e999e5baf07c4593 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 27, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 1th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.30 and later · before 5.10.252
  • linux linux kernel5.11 and later · before 5.15.202
  • linux linux kernel5.16 and later · before 6.1.165
  • linux linux kernel6.2 and later · before 6.6.128
  • linux linux kernel6.7 and later · before 6.12.75
  • linux linux kernel6.13 and later · before 6.18.14
  • linux linux kernel6.19 and later · before 6.19.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.30affected
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before b9abb760db20504240a7147f27934d900cd80b23affected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before 3a72c7dedc99b321e0f267e4e999e5baf07c4593affected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before 99e17b20fddac19a228d213e00f6b9e1c10daff9affected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before 243f71ed873ff3feeb6f9b5cb145d63f7188b4c4affected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before 063a6f22478ef929625000a2caf54667725c1dfdaffected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before d75ec4504a4340b033b15cad0303988b3089dd93affected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before 8dff54fe88c0dcd4c55bff9fc2fa6ca968290826affected · git
    • 2f425878b6a71571341dcd3f9e9d1a6f6355da9c and later · before f9c206cdc4266caad6a9a7f46341420a10f03ccbaffected · git
    • before 2.6.30not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.18.14-16.18.14-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-45981May 27, 2026 · s390/cio: Fix device lifecycle handling in css_alloc_subchannel()
    22Monitor
  • ← EarlierCVE-2026-45982May 27, 2026 · ACPICA: Fix NULL pointer dereference in acpi_ev_address_space_dispatch()
    22Monitor
  • Later →CVE-2026-45986May 27, 2026 · crypto: ccree - fix a memory leak in cc_mac_digest()
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux063a6f22478ef929625000a2caf54667725c1dfdVendor (CNA)
Linux Linux243f71ed873ff3feeb6f9b5cb145d63f7188b4c4Vendor (CNA)
Linux Linux3a72c7dedc99b321e0f267e4e999e5baf07c4593Vendor (CNA)
Linux Linux8dff54fe88c0dcd4c55bff9fc2fa6ca968290826Vendor (CNA)
Linux Linux99e17b20fddac19a228d213e00f6b9e1c10daff9Vendor (CNA)
Linux Linuxb9abb760db20504240a7147f27934d900cd80b23Vendor (CNA)
Linux Linuxd75ec4504a4340b033b15cad0303988b3089dd93Vendor (CNA)
Linux Linuxf9c206cdc4266caad6a9a7f46341420a10f03ccbVendor (CNA)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records