CVE-2026-89953 mtd: mtdoops: free page bitmap when the backing MTD is removed
A memory leak in the Linux kernel mtdoops driver allows local attackers to exhaust memory by repeatedly removing and re-adding MTD devices.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89953?
CVE-2026-89953 is a memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mtd: mtdoops: free page bitmap when the backing MTD is removed
mtdoops_notify_add() allocates oops_page_used when the configured MTD device is registered. mtdoops_notify_remove() detaches from that device but leaves the bitmap allocated. If the same MTD device is later registered again, the add path allocates a new bitmap and overwrites the old pointer, leaking one vmalloc allocation per remove/add cycle.
This is only visible when the backing MTD device can disappear and be registered again while mtdoops remains loaded, so the usual static MTD case does not expose it.
Free the bitmap after unregistering the dumper and flushing the pending workers, then clear the pointer and page count before a later attach can allocate fresh state. Clearing the pointer also keeps the module exit path from freeing the same bitmap a second time after a remove event.
Which versions are affected by CVE-2026-89953?
How do I fix CVE-2026-89953?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89953 being exploited?
There is no known exploitation of CVE-2026-89953 in the wild and no public exploit code.
Sources
Also known as AZL-101562, BELL-CVE-2026-89953, DEBIAN-CVE-2026-89953, GHSA-wvj7-v5wh-67w6, UBUNTU-CVE-2026-89953.