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NVD / CVE Program· CNA Linux

CVE-2025-40287: exfat: fix improper check of dentry.stream.valid_size

Noroxi assessment

Priority: Monitor (action score 0/100)

  • 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: 0.19% (FIRST EPSS).
  • Fixed version: Linux Linux 204b1b02ee018ba52ad2ece21fe3a8643d66a1b2, 6c627bcc1896ba62ec793d0c00da74f3c93ce3ad, 82ebecdc74ff555daf70b811d854b1f32a296bea.

Low priority for now. Upgrade to Linux Linux 204b1b02ee018ba52ad2ece21fe3a8643d66a1b2, 6c627bcc1896ba62ec793d0c00da74f3c93ce3ad, 82ebecdc74ff555daf70b811d854b1f32a296bea 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: exfat: fix improper check of dentry.stream.valid_size We found an infinite loop bug in the exFAT file system that can lead to a Denial-of-Service (DoS) condition. When a dentry in an exFAT filesystem is malformed, the following system calls — SYS_openat, SYS_ftruncate, and SYS_pwrite64 — can cause the kernel to hang. Root cause analysis shows that the size validation code in exfat_find() does not check whether dentry.stream.valid_size is negative. As a result, the system calls mentioned above can succeed and eventually trigger the DoS issue. This patch adds a check for negative dentry.stream.valid_size to prevent this vulnerability.

—No exploit Fix available
Published
Dec 6, 2025
Updated
Oct 15, 2026
EPSS
0.1% · 9th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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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.

—

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

    • 6.8affected
    • 11a347fb6cef62ce47e84b97c45f2b2497c7593b and later · before 6c627bcc1896ba62ec793d0c00da74f3c93ce3adaffected · git
    • 11a347fb6cef62ce47e84b97c45f2b2497c7593b and later · before 204b1b02ee018ba52ad2ece21fe3a8643d66a1b2affected · git
    • 11a347fb6cef62ce47e84b97c45f2b2497c7593b and later · before 82ebecdc74ff555daf70b811d854b1f32a296beaaffected · git
    • before 6.8not affected · semver
    • 6.12.59 and later · up to and including 6.12.*not affected · semver
    • 6.17.9 and later · up to and including 6.17.*not affected · semver
    • 6.18 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:13linuxbefore 6.12.63-16.12.63-1
Debian:14linuxbefore 6.17.9-16.17.9-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2025-40285Dec 6, 2025 · smb/server: fix possible refcount leak in smb2_sess_setup()
    30Monitor
  • ← EarlierCVE-2025-40286Dec 6, 2025 · smb/server: fix possible memory leak in smb2_read()
    0Monitor
  • Later →CVE-2025-40288Dec 6, 2025 · drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices
    0Monitor

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 Linux204b1b02ee018ba52ad2ece21fe3a8643d66a1b2Vendor (CNA)
Linux Linux6c627bcc1896ba62ec793d0c00da74f3c93ce3adVendor (CNA)
Linux Linux82ebecdc74ff555daf70b811d854b1f32a296beaVendor (CNA)
debian:linux6.12.63-1 · Debian:13Package 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

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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✗ → ✓

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References

Show all references (2 more)

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

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