What’s Vulnerable › Vulnerabilities

CVE-2021-34981: Linux Kernel Bluetooth CMTP Module Double Free Privilege Escalation Vulnerability

• Severity: medium (CVSS 6.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-07 · updated 2026-06-17
• Weakness: CWE-415

Description

Linux Kernel Bluetooth CMTP Module Double Free Privilege Escalation Vulnerability. This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel. An attacker must first obtain the ability to execute high-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the CMTP module. The issue results from the lack of validating the existence of an object prior to performing further free operations on the object. An attacker can leverage this vulnerability to escalate privileges and execute code in the context of the kernel. Was ZDI-CAN-11977.

Affected products

• Linux kernel: before 5.10.42 — fixed in 5.10.42

How to fix

Upgrade to a fixed version: Linux kernel 5.10.42. Check the vendor advisory for mitigations.

References

• https://www.zerodayinitiative.com/advisories/ZDI-21-1223/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1223/

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