CVE-2026-43497— fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free
Possible ATT&CK Techniques 1AI
T1055.008 · Ptrace System CallsAffected Version Matrix 12
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 7433914efd584b22bb49d3e1eee001f5d0525ecd< 4f312c30f0368e8d2a76aa650dff73f23490b5e7 | affected |
7433914efd584b22bb49d3e1eee001f5d0525ecd< 18dd358de72d57993422cbb5dfb29ccd74efe192 | affected | ||
7433914efd584b22bb49d3e1eee001f5d0525ecd< da9b065cedfd3b574f229d5be594e6aa47a27ae6 | affected | ||
7433914efd584b22bb49d3e1eee001f5d0525ecd< a2c53a3822ee26e8d758071815b9ed3bf6669fc1 | affected | ||
7433914efd584b22bb49d3e1eee001f5d0525ecd< 8de779dc40d35d39fa07387b6f921eb11df0f511 | affected | ||
4.19 | affected | ||
< 4.19 | unaffected | ||
6.6.140≤ 6.6.* | unaffected | ||
| … +4 more rows | |||
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I. Basic Information for CVE-2026-43497
Vulnerability Information
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Vulnerability Title
fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free
Source: NVD (National Vulnerability Database)
Vulnerability 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.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于fbdev: udlfb中dlfb_ops_mmap未设置vm_ops，导致内核无法跟踪活动mmap，在USB断开时可能发生释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-43497
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-43497 (5)
Same Patch Batch · Linux · 2026-05-21 · 8 CVEs total
| CVE-2026-43502 | net/rds: handle zerocopy send cleanup before the message is queued | |
| CVE-2026-43501 | ipv6: rpl: reserve mac_len headroom when recompressed SRH grows | |
| CVE-2026-43498 | accel/ivpu: Disallow re-exporting imported GEM objects | |
| CVE-2026-43499 | rtmutex: Use waiter::task instead of current in remove_waiter() | |
| CVE-2026-43496 | net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked | |
| CVE-2026-43495 | net: wwan: t7xx: validate port_count against message length in t7xx_port_enum_msg_handler | |
| CVE-2026-43494 | net/rds: reset op_nents when zerocopy page pin fails |
IV. Related Vulnerabilities
V. Comments for CVE-2026-43497
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