CVE-2026-43065
Memory Leak in Linux Kernel ext4 Filesystem
Publication date: 2026-05-05
Last updated on: 2026-05-05
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 exists in the Linux kernel's ext4 filesystem code, specifically in the handling of queued discard work in the ext4_mb_release() function.
When the filesystem is initially mounted with the discard option, deleting files queues discard work. If the filesystem is then remounted with the nodiscard option, the discard flag is cleared, but any pending discard work is neither cancelled nor processed (drained).
This can lead to queued discard operations remaining unhandled if the filesystem is unmounted immediately after remounting with nodiscard, which is a real bug fixed by this update.
However, triggering this issue deliberately is difficult and would require a specific sequence of mounting with discard, deleting many files, remounting with nodiscard, and unmounting quickly before the discard work drains.
How can this vulnerability impact me? :
The vulnerability could cause queued discard operations to remain unprocessed if the filesystem is remounted with the nodiscard option and then unmounted quickly.
This may lead to delayed or incomplete discard operations, potentially affecting filesystem performance or storage device behavior.
However, exploiting this issue deliberately is difficult and unlikely in typical usage scenarios.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability involves the ext4 filesystem discard work queue not being properly drained when remounting with the nodiscard option after initially mounting with discard.
Detection would require checking if the filesystem was mounted with the discard option, then remounted with nodiscard, and if there is pending discard work that has not been flushed.
However, the provided information does not include specific commands or tools to detect this condition on a system or network.
What immediate steps should I take to mitigate this vulnerability?
The vulnerability was fixed by ensuring that queued discard work is always drained in the ext4_mb_release() function.
Immediate mitigation would involve updating the Linux kernel to a version that includes this fix.
Additionally, avoid mounting the ext4 filesystem with the discard option and then remounting with nodiscard without allowing the discard work to drain, as this sequence triggers the issue.