CVE-2025-40155 iommu/vt-d: debugfs: Fix legacy mode page table dump logic
A local attacker with debugfs access can trigger a kernel crash by reading IOMMU page tables in legacy mode due to uninitialized pointer usage.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40155?
CVE-2025-40155 is a high-severity vulnerability in Linux, published on 12 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: debugfs: Fix legacy mode page table dump logic
In legacy mode, SSPTPTR is ignored if TT is not 00b or 01b. SSPTPTR maybe uninitialized or zero in that case and may cause oops like:
Oops: general protection fault, probably for non-canonical address 0xf00087d3f000f000: 0000 [#1] SMP NOPTI CPU: 2 UID: 0 PID: 786 Comm: cat Not tainted 6.16.0 #191 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-5.fc42 04/01/2014 RIP: 0010:pgtable_walk_level+0x98/0x150 RSP: 0018:ffffc90000f279c0 EFLAGS: 00010206 RAX: 0000000040000000 RBX: ffffc90000f27ab0 RCX: 000000000000001e RDX: 0000000000000003 RSI: f00087d3f000f000 RDI: f00087d3f0010000 RBP: ffffc90000f27a00 R08: ffffc90000f27a98 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000000 R12: f00087d3f000f000 R13: 0000000000000000 R14: 0000000040000000 R15: ffffc90000f27a98 FS: 0000764566dcb740(0000) GS:ffff8881f812c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000764566d44000 CR3: 0000000109d81003 CR4: 0000000000772ef0 PKRU: 55555554 Call Trace: <TASK> pgtable_walk_level+0x88/0x150 domain_translation_struct_show.isra.0+0x2d9/0x300 dev_domain_translation_struct_show+0x20/0x40 seq_read_iter+0x12d/0x490 ...
Avoid walking the page table if TT is not 00b or 01b.
Which versions are affected by CVE-2025-40155?
How do I fix CVE-2025-40155?
Apply the vendor's patch.
Is CVE-2025-40155 being exploited?
There is no known exploitation of CVE-2025-40155 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40155, DEBIAN-CVE-2025-40155, GHSA-x5w6-9frm-w2cc, ROOT-OS-DEBIAN-13-CVE-2025-40155, ROOT-OS-UBUNTU-2404-CVE-2025-40155, UBUNTU-CVE-2025-40155.