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Public proof of conceptFix available

CVE-2023-6546

Kernel: gsm multiplexing race condition leads to privilege escalation

A public proof of concept exists; no exploitation attested.

  • Published2023-12-21
  • Fixed in6.5
  • WeaknessCWE-362 · CWE-366

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A race condition was found in the GSM 0710 tty multiplexor in the Linux kernel. This issue occurs when two threads execute the GSMIOC_SETCONF ioctl on the same tty file descriptor with the gsm line discipline enabled, and can lead to a use-after-free problem on a struct gsm_dlci while restarting the gsm mux. This could allow a local unprivileged user to escalate their privileges on the system.

Timeline

dates in UTC
  1. 2023-12-2120:01CVE publishedCNA
  2. 2023-12-2120:15CVE publishedNVD
  3. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Versions per branch

NVD
Linux linux kernel
BranchAffectedFixed in
6.5< 6.56.5
6.5= 6.5no fix published
Redhat enterprise linux
BranchAffectedFixed in
8.0= 8.0no fix published
9.0= 9.0no fix published
Fedoraproject fedora
BranchAffectedFixed in
39.x= 39no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA43 products

As redhat, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

37 more products in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-04

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • bpftoolTuxCare:AlmaLinux:9.2all versions · fixed in 7.0.0-284.30.1.el9_2.tuxcare.els5
  • bpftoolRed Hat:rhel_eus:9.2::baseosall versions · fixed in 0:7.0.0-284.55.1.el9_2and 1 other package
  • bpftoolRed Hat:enterprise_linux:9::baseosall versions · fixed in 0:7.3.0-427.13.1.el9_4and 1 other package
  • bpftoolAlmaLinux:9all versions · fixed in 7.3.0-427.13.1.el9_4
  • bpftool-debuginfoRed Hat:rhel_eus:9.2::crball versions · fixed in 0:7.0.0-284.55.1.el9_2
  • bpftool-debuginfoRed Hat:rhel_eus:9.2::appstreamall versions · fixed in 0:7.0.0-284.55.1.el9_2
  • bpftool-debuginfoRed Hat:enterprise_linux:9::realtimeall versions · fixed in 0:7.3.0-427.13.1.el9_4
  • bpftool-debuginfoRed Hat:enterprise_linux:9::nfvall versions · fixed in 0:7.3.0-427.13.1.el9_4

211 more package ranges on OSV.dev

Vendor advisories

  • CVE-2023-6546 Red Hat Product Security1,477 products fixed · 22 known affected

    kernel: GSM multiplexing race condition leads to privilege escalation

    kernel-rt as a component of Red Hat Enterprise Linux 9 · kernel-rt-core as a component of Red Hat Enterprise Linux 9 · kernel-rt-debug as a component of Red Hat Enterprise Linux 9 · +19 more

  • RHSA-2024:4970 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: kpatch-patch-4_18_0-305_120_1 security update

  • RHSA-2024:2093 Red Hat Product Security63 products fixed

    Red Hat Security Advisory: security update Logging for Red Hat OpenShift - 5.7.13

  • RHSA-2024:2621 Red Hat Product Security120 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2024:2394 Red Hat Product Security279 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2024:1614 Red Hat Product Security30 products fixed

    Red Hat Security Advisory: kernel-rt security and bug fix update

6 more advisories

Full record on NVD

Fix

  1. Update Linux linux kernel to 6.5
  2. Vendor fix Red Hat Product Security RHSA-2024:4970 · 7 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  3. Vendor fix Red Hat Product Security RHSA-2024:2093 · 63 productsFor OpenShift Container Platform 4.11 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.openshift.com/container-platform/4.12/release_notes/ocp-4-12-release-not…
  4. Vendor fix Red Hat Product Security RHSA-2024:2621 · 120 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect.
  5. Workaround from the vendor Red Hat Product Security RHSA-2024:4970 · 7 productsThis flaw can be mitigated by preventing the affected `n_gsm` kernel module from being loaded. For instructions on how to blacklist a kernel module, please see https://access.redhat.com/solutions/41278.

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2023-12-21
Last Modified
2026-11-04
NVD status
Modified
GitHub Advisory
GHSA-v727-f437-6cxx

Frequently asked questions

What is CVE-2023-6546?

A race condition was found in the GSM 0710 tty multiplexor in the Linux kernel. This issue occurs when two threads execute the GSMIOC_SETCONF ioctl on the same tty file descriptor with the gsm line discipline enabled, and can lead to a use-after-free problem on a struct gsm_dlci while restarting the gsm mux. This could allow a local unprivileged user to escalate their privileges on the system.

Is CVE-2023-6546 actively exploited?

Active exploitation of CVE-2023-6546 has not been confirmed. Its EPSS score was 0.7% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2023-6546?

CVE-2023-6546 has a CVSS v3 base score of 7 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

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