CVE-2026-99007 drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99007?
CVE-2026-99007 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN
__drm_fb_helper_initial_config_and_unlock() calls drm_client_modeset_probe() first, which already fills in each mode_set->mode/num_connectors for every connected output, and only afterwards calls drm_fb_helper_single_fb_probe() to create fb_helper->fb and wire it into those mode_sets via drm_setup_crtcs_fb().
If drm_fb_helper_single_fb_probe() fails with anything other than -EAGAIN (e.g. dev->driver->fbdev_probe() itself fails), the function bails out before drm_setup_crtcs_fb() runs and before setting fb_helper->deferred_setup. The client is left with mode_sets that have a mode and connectors but mode_set->fb == NULL, and nothing marks this fb_helper as needing a retry.
__drm_fb_helper_restore_fbdev_mode_unlocked() only skips committing when fb_helper->deferred_setup is set, so a later .restore() call (drm_lastclose() on process exit, in this report) commits the stale mode_set through drm_client_modeset_commit() -> drm_client_modeset_commit_atomic() -> __drm_atomic_helper_set_config(), which hits WARN_ON(!set->fb).
Mark fb_helper->deferred_setup on any drm_fb_helper_single_fb_probe() failure, not just -EAGAIN, so restore keeps skipping the commit until a later hotplug event successfully re-probes and re-populates mode_set->fb. The real error code is still returned to the caller unchanged.
Which versions are affected by CVE-2026-99007?
How do I fix CVE-2026-99007?
Upgrade to a fixed version.
Is CVE-2026-99007 being exploited?
There is no known exploitation of CVE-2026-99007 in the wild and no public exploit code.
Sources
Also known as AZL-110849, BELL-CVE-2026-99007, DEBIAN-CVE-2026-99007, GHSA-g687-j9p7-p4rx, UBUNTU-CVE-2026-99007.