CVE-2026-43497
Description
In the Linux kernel, the following vulnerability has been resolved: fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free dlfb_ops_mmap() uses remap_pfn_range() to map vmalloc framebuffer pages to userspace but sets no vm_ops on the VMA. This means the kernel cannot track active mmaps. When dlfb_realloc_framebuffer() replaces the backing buffer via FBIOPUT_VSCREENINFO, existing mmap PTEs are not invalidated. On USB disconnect, dlfb_ops_destroy() calls vfree() on the old pages while userspace PTEs still reference them, resulting in a use-after-free: the process retains read/write access to freed kernel pages. Add vm_operations_struct with open/close callbacks that maintain an atomic mmap_count on struct dlfb_data. In dlfb_realloc_framebuffer(), check mmap_count and return -EBUSY if the buffer is currently mapped, preventing buffer replacement while userspace holds stale PTEs. Tested with PoC using dummy_hcd + raw_gadget USB device emulation.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Windows Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Mixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 6.12.88-1 |
| sid | Fixed | 7.0.7-1 |
| forky | Fixed | 7.0.7-1 |
| bullseye | Affected | — |
| bookworm | Affected | — |
References
- https://git.kernel.org/stable/c/18dd358de72d57993422cbb5dfb29ccd74efe192
- https://git.kernel.org/stable/c/4f312c30f0368e8d2a76aa650dff73f23490b5e7
- https://git.kernel.org/stable/c/8de779dc40d35d39fa07387b6f921eb11df0f511
- https://git.kernel.org/stable/c/a2c53a3822ee26e8d758071815b9ed3bf6669fc1
- https://git.kernel.org/stable/c/da9b065cedfd3b574f229d5be594e6aa47a27ae6
- https://www.suse.com/security/cve/CVE-2026-43497.html
- https://security-tracker.debian.org/tracker/CVE-2026-43497
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-43497
- https://git.kernel.org/stable/c/5931f5651ee32bd41b3323256b31fcc8e71336ed
- https://git.kernel.org/stable/c/60f711cfd580f86fea8284146ac133804e728f9a
- https://git.kernel.org/stable/c/e3d9865dacd7435b8465848428210d0f0c673311
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.