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NVD / CVE Program· CNA Linux

CVE-2026-43116: netfilter: ctnetlink: ensure safe access to master conntrack

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.10% (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 497f99b26fffdc5635706d1b4811f1ed8ee21a5b, 5e1c1d22268ae710c238342c8030c21daf298168, 9e1196d27ef496f404c76f7a9d03761142d991c4.

Low priority for now. Upgrade to Linux Linux 497f99b26fffdc5635706d1b4811f1ed8ee21a5b, 5e1c1d22268ae710c238342c8030c21daf298168, 9e1196d27ef496f404c76f7a9d03761142d991c4 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: ensure safe access to master conntrack Holding reference on the expectation is not sufficient, the master conntrack object can just go away, making exp->master invalid. To access exp->master safely: - Grab the nf_conntrack_expect_lock, this gets serialized with clean_from_lists() which also holds this lock when the master conntrack goes away. - Hold reference on master conntrack via nf_conntrack_find_get(). Not so easy since the master tuple to look up for the master conntrack is not available in the existing problematic paths. This patch goes for extending the nf_conntrack_expect_lock section to address this issue for simplicity, in the cases that are described below this is just slightly extending the lock section. The add expectation command already holds a reference to the master conntrack from ctnetlink_create_expect(). However, the delete expectation command needs to grab the spinlock before looking up for the expectation. Expand the existing spinlock section to address this to cover the expectation lookup. Note that, the nf_ct_expect_iterate_net() calls already grabs the spinlock while iterating over the expectation table, which is correct. The get expectation command needs to grab the spinlock to ensure master conntrack does not go away. This also expands the existing spinlock section to cover the expectation lookup too. I needed to move the netlink skb allocation out of the spinlock to keep it GFP_KERNEL. For the expectation events, the IPEXP_DESTROY event is already delivered under the spinlock, just move the delivery of IPEXP_NEW under the spinlock too because the master conntrack event cache is reached through exp->master. While at it, add lockdep notations to help identify what codepaths need to grab the spinlock.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
May 6, 2026
Updated
Nov 10, 2026
EPSS
0.1% · 0th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

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

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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 kernel2.6.16 and later · before 6.18.24
  • linux linux kernel6.19 and later · before 6.19.14
  • linux linux kernel7.0

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

    • 2.6.16affected
    • c1d10adb4a521de5760112853f42aaeefcec96eb and later · before 9e1196d27ef496f404c76f7a9d03761142d991c4affected · git
    • c1d10adb4a521de5760112853f42aaeefcec96eb and later · before 5e1c1d22268ae710c238342c8030c21daf298168affected · git
    • c1d10adb4a521de5760112853f42aaeefcec96eb and later · before d52fa1fa7440676b8c238037a050ab008c22737faffected · git
    • c1d10adb4a521de5760112853f42aaeefcec96eb and later · before f338ced0473849c9f6ed0b77ca99f1aab5826787affected · git
    • c1d10adb4a521de5760112853f42aaeefcec96eb and later · before 497f99b26fffdc5635706d1b4811f1ed8ee21a5baffected · git
    • c1d10adb4a521de5760112853f42aaeefcec96eb and later · before bffcaad9afdfe45d7fc777397d3b83c1e3ebffe5affected · git
    • before 2.6.16not affected · semver
    • 6.1.176 and later · up to and including 6.1.*not affected · semver
    • 6.6.143 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2

+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-2026-43114May 6, 2026 · netfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry
    37Monitor
  • ← EarlierCVE-2026-43115May 6, 2026 · srcu: Use irq_work to start GP in tiny SRCU
    22Monitor
  • Later →CVE-2026-43117May 6, 2026 · btrfs: tracepoints: get correct superblock from dentry in event btrfs_sync_file()
    36Monitor

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 Linux497f99b26fffdc5635706d1b4811f1ed8ee21a5bVendor (CNA)
Linux Linux5e1c1d22268ae710c238342c8030c21daf298168Vendor (CNA)
Linux Linux9e1196d27ef496f404c76f7a9d03761142d991c4Vendor (CNA)
Linux Linuxbffcaad9afdfe45d7fc777397d3b83c1e3ebffe5Vendor (CNA)
Linux Linuxd52fa1fa7440676b8c238037a050ab008c22737fVendor (CNA)
Linux Linuxf338ced0473849c9f6ed0b77ca99f1aab5826787Vendor (CNA)
almalinux:kernel6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.18.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch646.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-64kb6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-azure6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default-base6.12.0-160000.38.1.160000.2.22 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-docs6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-kvmsmall6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-build6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-qa6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-rt6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-source6.12.0-160000.38.1 · openSUSE:Leap 16.0Package registry (OSV)

+29

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
high · data or configuration can be modified
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
High
Availability impact
High

Weakness class (CWE)

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

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

nvd-secondary

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. SSVC exploitation— → none
  2. 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