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NVD / CVE Program· CNA Linux

CVE-2023-53606: nfsd: clean up potential nfsd_file refcount leaks in COPY codepath

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: 0.28% (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.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191f, 75b8c681c563ef7e85da6862354efc18d2a08b1b, 8f565846fbe8182961498d4cbe618b15076a683b.
  • Severity is disputed: the assigning authority (CNA) scores it 7.5, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191f, 75b8c681c563ef7e85da6862354efc18d2a08b1b, 8f565846fbe8182961498d4cbe618b15076a683b 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: clean up potential nfsd_file refcount leaks in COPY codepath There are two different flavors of the nfsd4_copy struct. One is embedded in the compound and is used directly in synchronous copies. The other is dynamically allocated, refcounted and tracked in the client struture. For the embedded one, the cleanup just involves releasing any nfsd_files held on its behalf. For the async one, the cleanup is a bit more involved, and we need to dequeue it from lists, unhash it, etc. There is at least one potential refcount leak in this code now. If the kthread_create call fails, then both the src and dst nfsd_files in the original nfsd4_copy object are leaked. The cleanup in this codepath is also sort of weird. In the async copy case, we'll have up to four nfsd_file references (src and dst for both flavors of copy structure). They are both put at the end of nfsd4_do_async_copy, even though the ones held on behalf of the embedded one outlive that structure. Change it so that we always clean up the nfsd_file refs held by the embedded copy structure before nfsd4_copy returns. Rework cleanup_async_copy to handle both inter and intra copies. Eliminate nfsd4_cleanup_intra_ssc since it now becomes a no-op.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Oct 4, 2025
Updated
Oct 15, 2026
EPSS
0.2% · 21th 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 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
7.5
2.0 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

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Follow CVE-2023-53606

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
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  • 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 kernel4.20 and later · before 5.10.220
  • linux linux kernel5.11 and later · before 5.15.154
  • linux linux kernel5.16 and later · before 6.1.16
  • linux linux kernel6.2 and later · before 6.2.3

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

    • 4.20affected
    • e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 and later · before fd63299db8090307eae66f2aef17c8f00aafa0a9affected · git
    • e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 and later · before b3169b6ffe036b549c296a9e71591d29a1fb3209affected · git
    • e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 and later · before 75b8c681c563ef7e85da6862354efc18d2a08b1baffected · git
    • e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 and later · before 8f565846fbe8182961498d4cbe618b15076a683baffected · git
    • e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 and later · before 6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191faffected · git
    • before 4.20not affected · semver
    • 5.10.220 and later · up to and including 5.10.*not affected · semver
    • 5.15.154 and later · up to and including 5.15.*not affected · semver
    • 6.1.16 and later · up to and including 6.1.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.20-16.1.20-1

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-2023-53598Oct 4, 2025 · bus: mhi: host: Range check CHDBOFF and ERDBOFF
    22Monitor
  • ← EarlierCVE-2023-53600Oct 4, 2025 · tunnels: fix kasan splat when generating ipv4 pmtu error
    28Monitor
  • Later →CVE-2023-53609Oct 4, 2025 · scsi: Revert "scsi: core: Do not increase scsi_device's iorequest_cnt if dispatch failed"
    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 Linux6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191fVendor (CNA)
Linux Linux75b8c681c563ef7e85da6862354efc18d2a08b1bVendor (CNA)
Linux Linux8f565846fbe8182961498d4cbe618b15076a683bVendor (CNA)
Linux Linuxb3169b6ffe036b549c296a9e71591d29a1fb3209Vendor (CNA)
Linux Linuxfd63299db8090307eae66f2aef17c8f00aafa0a9Vendor (CNA)
debian:linux6.1.20-1 · 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).

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. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (4 more)

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

All records