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CVE-2025-39764· NVD / CVE Program· CNA Linux

netfilter: ctnetlink: remove refcounting in expectation dumpers

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: 0.16% (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 078d33c95bf534d37aa04269d1ae6158e20082d5, 1492e3dcb2be3aa46d1963da96aa9593e4e4db5a, 64b7684042246e3238464c66894e30ba30c7e851; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes.

Low priority for now. Upgrade to Linux Linux 078d33c95bf534d37aa04269d1ae6158e20082d5, 1492e3dcb2be3aa46d1963da96aa9593e4e4db5a, 64b7684042246e3238464c66894e30ba30c7e851; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes 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: netfilter: ctnetlink: remove refcounting in expectation dumpers Same pattern as previous patch: do not keep the expectation object alive via refcount, only store a cookie value and then use that as the skip hint for dump resumption. AFAICS this has the same issue as the one resolved in the conntrack dumper, when we do if (!refcount_inc_not_zero(&exp->use)) to increment the refcount, there is a chance that exp == last, which causes a double-increment of the refcount and subsequent memory leak.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 11, 2025
Updated
Sep 8, 2026
EPSS
0.2% · 6th 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%

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

  • when it enters CISA KEV
  • 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 kernel2.6.23 and later · before 6.16.2
  • 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

    • 2.6.23affected
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before b05500444b8eb97644efdd180839a04a706be97caffected · git
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before bada48ad5b0590e318d0f79636ff62a2ef9f4955affected · git
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before 64b7684042246e3238464c66894e30ba30c7e851affected · git
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before 9e5021a906532ca16e2aac69c0607711e1c70b1faffected · git
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before 078d33c95bf534d37aa04269d1ae6158e20082d5affected · git
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before a4d634ded4d3d400f115d84f654f316f249531c9affected · git
    • cf6994c2b9812a9f02b99e89df411ffc5db9c779 and later · before 1492e3dcb2be3aa46d1963da96aa9593e4e4db5aaffected · git
    • before 2.6.23not affected · semver
    • 5.10.253 and later · up to and including 5.10.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.16.3-16.16.3-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

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    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now
  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now
  • CVE-2019-13272In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to creKEV
    77This week
  • CVE-2013-6282The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the v6k and v7 ARM platforms do not validate certain addKEV
    77This week
  • CVE-2013-2094The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9 uses an incorrect integer data type, which allows loKEV
    77This week

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 Linux078d33c95bf534d37aa04269d1ae6158e20082d5Vendor (CNA)
Linux Linux1492e3dcb2be3aa46d1963da96aa9593e4e4db5aVendor (CNA)
Linux Linux64b7684042246e3238464c66894e30ba30c7e851Vendor (CNA)
Linux Linux9e5021a906532ca16e2aac69c0607711e1c70b1fVendor (CNA)
Linux Linuxa4d634ded4d3d400f115d84f654f316f249531c9Vendor (CNA)
Linux Linuxb05500444b8eb97644efdd180839a04a706be97cVendor (CNA)
Linux Linuxbada48ad5b0590e318d0f79636ff62a2ef9f4955Vendor (CNA)
cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0Release NotesMicrosoft (MSRC)
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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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