CVE-2026-43437
Use-After-Free in Linux Kernel ALSA PCM Subsystem
Publication date: 2026-05-08
Last updated on: 2026-05-08
Assigner: kernel.org
Description
Description
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a use-after-free issue in the Linux kernel's ALSA pcm component, specifically in the snd_pcm_drain() function. During the drain loop, a local variable 'runtime' is reassigned to a linked stream's runtime. After releasing the stream lock, the code accesses fields of this linked stream's runtime without any lock or reference count to protect its lifetime.
If a concurrent close() operation occurs on the linked stream's file descriptor, it can trigger a sequence of functions that eventually free the runtime memory (kfree(runtime)). Because there is no synchronization, the drain path may dereference a pointer to memory that has already been freed, leading to a use-after-free condition.
The fix involves caching the needed runtime fields into local variables while still holding the stream lock, and then using these cached values after the lock is released to avoid accessing freed memory.
How can this vulnerability impact me? :
This use-after-free vulnerability can lead to undefined behavior in the Linux kernel, such as system crashes, memory corruption, or potential escalation of privileges if exploited. It may cause instability or denial of service in systems using the ALSA pcm audio subsystem.
What immediate steps should I take to mitigate this vulnerability?
The vulnerability is fixed by updating the Linux kernel to a version where the ALSA pcm drain use-after-free issue is resolved.
Specifically, the fix involves caching the needed runtime fields while holding the stream lock to prevent accessing freed memory.
Therefore, the immediate mitigation step is to apply the kernel update or patch that includes this fix.