CVE-2020-11725 in Linux
Summary
by MITRE
snd_ctl_elem_add in sound/core/control.c in the Linux kernel through 5.6.3 has a count=info->owner line, which later affects a private_size*count multiplication for unspecified "interesting side effects." NOTE: kernel engineers dispute this finding, because it could be relevant only if new callers were added that were unfamiliar with the misuse of the info->owner field to represent data unrelated to the "owner" concept. The existing callers, SNDRV_CTL_IOCTL_ELEM_ADD and SNDRV_CTL_IOCTL_ELEM_REPLACE, have been designed to misuse the info->owner field in a safe way
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Analysis
by VulDB Data Team • 05/30/2026
The vulnerability identified as CVE-2020-11725 resides within the Linux kernel's sound subsystem, specifically in the snd_ctl_elem_add function located in sound/core/control.c. This flaw represents a critical memory management issue that affects kernel versions through 5.6.3, potentially enabling privilege escalation and system instability. The vulnerability stems from a fundamental programming error where the count parameter is incorrectly assigned from info->owner instead of the intended value, creating a cascading effect that compromises the kernel's memory allocation mechanisms.
The technical implementation of this vulnerability involves a multiplication operation between private_size and count parameters that becomes fundamentally flawed due to the incorrect assignment. When the count variable contains the value from info->owner rather than the proper element count, the multiplication private_size*count produces an unexpectedly large or invalid memory allocation request. This error occurs during the dynamic allocation of control elements within the ALSA (Advanced Linux Sound Architecture) subsystem, which is responsible for handling audio device control interfaces. The misassignment creates a scenario where kernel memory is allocated based on an incorrect multiplier, potentially leading to buffer overflows, memory corruption, or allocation failures that can be exploited by malicious actors.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a potential privilege escalation vector within the Linux kernel environment. Attackers with local access could leverage this flaw to manipulate kernel memory structures, potentially gaining elevated privileges or causing system crashes that result in denial of service conditions. The vulnerability's exploitation requires local system access but can lead to significant security implications given that the kernel operates with the highest privilege levels. This flaw affects the fundamental audio control infrastructure of Linux systems, potentially impacting desktop environments, servers, and embedded systems that rely on ALSA for audio functionality.
Mitigation strategies for CVE-2020-11725 involve immediate patching of affected kernel versions to address the typo in the count parameter assignment within the snd_ctl_elem_add function. System administrators should prioritize updating their kernel installations to versions that contain the fix, which typically involves correcting the assignment from info->owner to the proper count value. Additionally, organizations should implement monitoring for unusual memory allocation patterns or kernel panic events that might indicate exploitation attempts. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a memory safety issue that can be addressed through proper input validation and parameter checking. From an ATT&CK perspective, this vulnerability could be categorized under privilege escalation techniques, specifically T1068, where attackers leverage kernel-level flaws to gain elevated system privileges, making it a significant concern for enterprise security teams managing Linux-based infrastructure.