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NVD / CVE Program· CNA Linux

CVE-2025-37871: nfsd: decrease sc_count directly if fail to queue dl_recall

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: 0.77% (FIRST EPSS); higher than 55.8% of all records.
  • 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 14985d66b9b99c12995dd99d1c6c8dec4114c2a5, 5.10.237, 5.15.181.
  • Severity is disputed: the assigning authority (CNA) scores it 7.5, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 14985d66b9b99c12995dd99d1c6c8dec4114c2a5, 5.10.237, 5.15.181 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: decrease sc_count directly if fail to queue dl_recall A deadlock warning occurred when invoking nfs4_put_stid following a failed dl_recall queue operation: T1 T2 nfs4_laundromat nfs4_get_client_reaplist nfs4_anylock_blockers __break_lease spin_lock // ctx->flc_lock spin_lock // clp->cl_lock nfs4_lockowner_has_blockers locks_owner_has_blockers spin_lock // flctx->flc_lock nfsd_break_deleg_cb nfsd_break_one_deleg nfs4_put_stid refcount_dec_and_lock spin_lock // clp->cl_lock When a file is opened, an nfs4_delegation is allocated with sc_count initialized to 1, and the file_lease holds a reference to the delegation. The file_lease is then associated with the file through kernel_setlease. The disassociation is performed in nfsd4_delegreturn via the following call chain: nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg --> nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease The corresponding sc_count reference will be released after this disassociation. Since nfsd_break_one_deleg executes while holding the flc_lock, the disassociation process becomes blocked when attempting to acquire flc_lock in generic_delete_lease. This means: 1) sc_count in nfsd_break_one_deleg will not be decremented to 0; 2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to acquire cl_lock; 3) Consequently, no deadlock condition is created. Given that sc_count in nfsd_break_one_deleg remains non-zero, we can safely perform refcount_dec on sc_count directly. This approach effectively avoids triggering deadlock warnings.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 9, 2025
Updated
Aug 5, 2026
EPSS
0.7% · 55th 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 · 0.7%

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.

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  • 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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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
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • linux linux kernel6.13.11 and later · before 6.14
  • linux linux kernel6.14.2 and later · before 6.14.4
  • linux linux kernel6.12.23 and later · before 6.12.25
  • linux linux kernel5.10.236
  • linux linux kernel5.15.180
  • linux linux kernel6.1.134
  • linux linux kernel6.15
  • linux linux kernel6.6.87

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

    • 63b91c8ff4589f5263873b24c052447a28e10ef7affected
    • b874cdef4e67e5150e07eff0eae1cbb21fb92da1 and later · before b9bbe8f9d5663311d06667ce36d6ed255ead1a26affected · git
    • cdb796137c57e68ca34518d53be53b679351eb86 and later · before a70832d3555987035fc430ccd703acd89393eadbaffected · git
    • d96587cc93ec369031bcd7658c6adc719873c9fd and later · before ba903539fff745d592d893c71b30e5e268a95413affected · git
    • 9a81cde8c7ce65dd90fb47ceea93a45fc1a2fbd1 and later · before 7d192e27a431026c58d60edf66dc6cd98d0c01fcaffected · git
    • cad3479b63661a399c9df1d0b759e1806e2df3c8 and later · before a7fce086f6ca84db409b9d58493ea77c1978897caffected · git
    • 133f5e2a37ce08c82d24e8fba65e0a81deae4609 and later · before 14985d66b9b99c12995dd99d1c6c8dec4114c2a5affected · git
    • 230ca758453c63bd38e4d9f4a21db698f7abada8 and later · before a1d14d931bf700c1025db8c46d6731aa5cf440f9affected · git
    • 6.13.11 and later · before 6.14affected · semver
    • 5.10.236 and later · before 5.10.237affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.135-16.1.135-1
Debian:13linuxbefore 6.12.25-16.12.25-1

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-2025-37867May 9, 2025 · RDMA/core: Silence oversized kvmalloc() warning
    22Monitor
  • ← EarlierCVE-2025-37868May 9, 2025 · drm/xe/userptr: fix notifier vs folio deadlock
    22Monitor
  • Later →CVE-2025-37872May 9, 2025 · net: txgbe: fix memory leak in txgbe_probe() error path
    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 Linux14985d66b9b99c12995dd99d1c6c8dec4114c2a5Vendor (CNA)
Linux Linux5.10.237Vendor (CNA)
Linux Linux5.15.181Vendor (CNA)
Linux Linux6.1.135Vendor (CNA)
Linux Linux6.12.25Vendor (CNA)
Linux Linux6.14Vendor (CNA)
Linux Linux6.14.4Vendor (CNA)
Linux Linux6.6.88Vendor (CNA)
Linux Linux7d192e27a431026c58d60edf66dc6cd98d0c01fcVendor (CNA)
Linux Linuxa1d14d931bf700c1025db8c46d6731aa5cf440f9Vendor (CNA)
Linux Linuxa70832d3555987035fc430ccd703acd89393eadbVendor (CNA)
Linux Linuxa7fce086f6ca84db409b9d58493ea77c1978897cVendor (CNA)
Linux Linuxb9bbe8f9d5663311d06667ce36d6ed255ead1a26Vendor (CNA)
Linux Linuxba903539fff745d592d893c71b30e5e268a95413Vendor (CNA)
debian:linux6.1.135-1 · 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. Fix✗ → ✓

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

References

Show all references (8 more)

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

All records