CVE-2023-6546: Kernel: gsm multiplexing race condition leads to privilege escalation

Ubuntu release	Source package	Vendor state	Fixed version	Evidence
Ubuntu 24.04 LTSnoble · standard archive	`linux-raspi-realtime`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 8 Sept 2026

Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available

What, why and how

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.

What

Why

If two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Why

If two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: local access → Race Condition within a Thread → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Local
Privileges required: Low: a basic authenticated account is required
User interaction: None
Attack complexity: High: exploitation depends on specific conditions
Security boundary: Unchanged: impact remains within the vulnerable component's security authority
Weakness ? CWE means Common Weakness Enumeration: a standard category for the underlying weakness.: CWE-366 ↗
CWE-366: Race Condition within a Thread. If two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land: The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.

CWE-366

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2023-58776Official EUVD mapping

0 linked advisory records.

Official EUVD record

BSI · German · WID-SEC-W-2024-1226Red Hat OpenShift: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Red Hat OpenShift ausnutzen, um Dateien zu manipulieren, einen Denial-of-Service-Zustand zu verursachen, beliebigen Code auszuführen, vertrauliche Informationen offenzulegen, seine Privilegien zu erweitern oder um weitere nicht spezifizierte Angriffe auszuführen.

Kernel: gsm multiplexing race condition leads to privilege escalation

National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

EUVD-2023-58776

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

National CERT insights
?
CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.