Local privilege escalation via unlocked GSM cleanup
Published Dec 21, 2023 · Updated Aug 6, 2026
Race condition in the Linux kernel GSM 0710 tty multiplexor allows local users to escalate privileges through concurrent ioctl calls. In gsm_cleanup_mux(), code reads gsm->dlci[0] before acquiring gsm->mutex, allowing another thread to release the referenced gsm_dlci before it is used. Exploitation requires low-privileged local code execution, the n_gsm line discipline, and a successful high-complexity race; successful exploitation executes code in the kernel context.
Summary
What happened
Race condition in the Linux kernel GSM 0710 tty multiplexor allows local users to escalate privileges through concurrent ioctl calls. In gsm_cleanup_mux(), code reads gsm->dlci[0] before acquiring gsm->mutex, allowing another thread to release the referenced gsm_dlci before it is used. Exploitation requires low-privileged local code execution, the n_gsm line discipline, and a successful high-complexity race; successful exploitation executes code in the kernel context.
The record
- CVE
- CVE-2023-6546
- Published
- Dec 21, 2023
- Updated
- Aug 6, 2026
- Vendor
- Red Hat
- Product
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- Classifications
- CWE-366, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 21, 2023CVE publishedPublication date reported by the CVE source.
- Aug 6, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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