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NVD / CVE Program· CNA Linux

CVE-2025-39840: audit: fix out-of-bounds read in audit_compare_dname_path()

Noroxi assessment

Priority: Monitor (action score 28/100)

  • 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: 0.15% (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 4540f1d23e7f387880ce46d11b5cd3f27248bf8d, 9735a9dcc307427e7d6336c54171682f1bac9789.

Low priority for now. Upgrade to Linux Linux 4540f1d23e7f387880ce46d11b5cd3f27248bf8d, 9735a9dcc307427e7d6336c54171682f1bac9789 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: audit: fix out-of-bounds read in audit_compare_dname_path() When a watch on dir=/ is combined with an fsnotify event for a single-character name directly under / (e.g., creating /a), an out-of-bounds read can occur in audit_compare_dname_path(). The helper parent_len() returns 1 for "/". In audit_compare_dname_path(), when parentlen equals the full path length (1), the code sets p = path + 1 and pathlen = 1 - 1 = 0. The subsequent loop then dereferences p[pathlen - 1] (i.e., p[-1]), causing an out-of-bounds read. Fix this by adding a pathlen > 0 check to the while loop condition to prevent the out-of-bounds access. [PM: subject tweak, sign-off email fixes]

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
Sep 19, 2025
Updated
Oct 19, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.1
CNA · Linux
7.1
agree

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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  • 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 kernel6.14 and later · before 6.16.6
  • linux linux kernel6.17

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

    • 6.14affected
    • e92eebb0d6116f942ab25dfb1a41905aa59472a8 and later · before 9735a9dcc307427e7d6336c54171682f1bac9789affected · git
    • e92eebb0d6116f942ab25dfb1a41905aa59472a8 and later · before 4540f1d23e7f387880ce46d11b5cd3f27248bf8daffected · git
    • before 6.14not affected · semver
    • 6.16.6 and later · up to and including 6.16.*not affected · semver
    • 6.17 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
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-124.27.1.el10_16.12.0-124.27.1.el10_1
AlmaLinux:10kernel-docbefore 6.12.0-124.27.1.el10_16.12.0-124.27.1.el10_1
AlmaLinux:9kernelbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64kbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-corebefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debugbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debug-corebefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debug-develbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debug-devel-matchedbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debug-modulesbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debug-modules-corebefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-debug-modules-extrabefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-develbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-devel-matchedbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-modulesbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-modules-corebefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-64k-modules-extrabefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-abi-stablelistsbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-corebefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-cross-headersbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-debugbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-debug-corebefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-debug-develbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7
AlmaLinux:9kernel-debug-devel-matchedbefore 5.14.0-611.20.1.el9_75.14.0-611.20.1.el9_7

+96

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-2025-39838Sep 19, 2025 · cifs: prevent NULL pointer dereference in UTF16 conversion
    22Monitor
  • ← EarlierCVE-2025-39839Sep 19, 2025 · batman-adv: fix OOB read/write in network-coding decode
    28Monitor
  • Later →CVE-2025-39841Sep 19, 2025 · scsi: lpfc: Fix buffer free/clear order in deferred receive path
    31Monitor

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 Linux4540f1d23e7f387880ce46d11b5cd3f27248bf8dVendor (CNA)
Linux Linux9735a9dcc307427e7d6336c54171682f1bac9789Vendor (CNA)
almalinux:kernel5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-611.20.1.el9_7 · AlmaLinux:9Package registry (OSV)
debian:linux6.16.6-1 · Debian:14Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel-matched0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-debuginfo0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel-matched0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debuginfo0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debuginfo-common-aarch640:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debuginfo-common-ppc64le0:5.14.0-611.20.1.el9_7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
rocky linux:kernel0:5.14.0-611.20.1.el9_7 · Rocky Linux:9Package 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
high · data can be read
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
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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

References

Show all references (1 more)

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

All records