CVE-2026-43497
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.11%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.3 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 0.11% probability · 2th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/18dd358de72d57993422cbb5dfb29ccd74efe192Patch
- https://git.kernel.org/stable/c/4f312c30f0368e8d2a76aa650dff73f23490b5e7Patch
- https://git.kernel.org/stable/c/5931f5651ee32bd41b3323256b31fcc8e71336edPatch
- https://git.kernel.org/stable/c/60f711cfd580f86fea8284146ac133804e728f9aPatch
- https://git.kernel.org/stable/c/8de779dc40d35d39fa07387b6f921eb11df0f511Patch
- https://git.kernel.org/stable/c/a2c53a3822ee26e8d758071815b9ed3bf6669fc1Patch
- https://git.kernel.org/stable/c/da9b065cedfd3b574f229d5be594e6aa47a27ae6Patch
- https://git.kernel.org/stable/c/e3d9865dacd7435b8465848428210d0f0c673311Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.