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CVE-2023-4206· NVD / CVE Program· CNA Google

Use-after-free in Linux kernel's net/sched: cls_route component

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: 0.58% (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 (Debian:12) 6.1.52-1; linux (Debian:13) 6.4.11-1; bpftool (Red Hat:enterprise_linux:7::client) 0:3.10.0-1160.105.1.el7.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to linux (Debian:12) 6.1.52-1; linux (Debian:13) 6.4.11-1; bpftool (Red Hat:enterprise_linux:7::client) 0:3.10.0-1160.105.1.el7 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

A use-after-free vulnerability in the Linux kernel's net/sched: cls_route component can be exploited to achieve local privilege escalation. When route4_change() is called on an existing filter, the whole tcf_result struct is always copied into the new instance of the filter. This causes a problem when updating a filter bound to a class, as tcf_unbind_filter() is always called on the old instance in the success path, decreasing filter_cnt of the still referenced class and allowing it to be deleted, leading to a use-after-free. We recommend upgrading past commit b80b829e9e2c1b3f7aae34855e04d8f6ecaf13c8.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Sep 6, 2023
Updated
Jun 17, 2026
EPSS
0.5% · 47th 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 · 0.5%

CNA vs NVD score

NVD
7.8
CNA · Google
7.8
agree

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

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.

Follow CVE-2023-4206

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
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 linux12.0
  • linux linux kernel4.15 and later · before 4.19.291
  • linux linux kernel4.20 and later · before 5.4.253
  • linux linux kernel5.5 and later · before 5.10.190
  • linux linux kernel3.18 and later · before 4.14.322
  • linux linux kernel5.16 and later · before 6.1.45
  • linux linux kernel6.2 and later · before 6.4.10
  • linux linux kernel5.11 and later · before 5.15.126

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Google). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Kernel

    • 3.18 and later · before 6.5affected

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.52-16.1.52-1
Debian:13linuxbefore 6.4.11-16.4.11-1
Red Hat:enterprise_linux:7::clientbpftoolbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientbpftool-debuginfobefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernelbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-abi-whitelistsbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-debugbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-debug-debuginfobefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-debug-develbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-debuginfobefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-debuginfo-common-x86_64before 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-develbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-docbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-toolsbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-tools-debuginfobefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-tools-libsbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientkernel-tools-libs-develbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientperfbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientperf-debuginfobefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientpython-perfbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::clientpython-perf-debuginfobefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::serverkernel-bootwrapperbefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::serverkernel-debuginfo-common-ppc64before 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7
Red Hat:enterprise_linux:7::serverkernel-debuginfo-common-ppc64lebefore 0:3.10.0-1160.105.1.el70:3.10.0-1160.105.1.el7

+96

Other highest-scoring records for the same primary product.

  • 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
  • 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

Published before and after this one in the same product

  • ← EarlierCVE-2023-4569Aug 28, 2023 · Kernel: information leak in nft_set_catchall_flush in net/netfilter/nf_tables_api.c
    22Monitor
  • ← EarlierCVE-2023-4611Aug 29, 2023 · Use after free race between mbind() and vma-locked page fault
    25Monitor
  • Later →CVE-2023-4207Sep 6, 2023 · Use-after-free in Linux kernel's net/sched: cls_fw component
    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
debian:linux6.1.52-1 · Debian:12Package registry (OSV)
red hat:bpftool-debuginfo0:7.0.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-devel-matched0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-debug-debuginfo0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-debug-devel0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-debug-devel-matched0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-debuginfo0:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:kernel-debuginfo-common-aarch640:5.14.0-284.40.1.el9_2 · Red Hat:rhel_eus:9.2::appstreamPackage 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.

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

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

All records