CVE-2025-40159 xsk: Harden userspace-supplied xdp_desc validation
Integer overflows in Linux kernel XSK descriptor validation allow attackers to cause undefined behavior or queue invalid frames, potentially leading to crashes or code execution.
- 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-2025-40159?
CVE-2025-40159 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:
xsk: Harden userspace-supplied xdp_desc validation
Turned out certain clearly invalid values passed in xdp_desc from userspace can pass xp_{,un}aligned_validate_desc() and then lead to UBs or just invalid frames to be queued for xmit.
desc->len close to ``U32_MAX`` with a non-zero pool->tx_metadata_len can cause positive integer overflow and wraparound, the same way low enough desc->addr with a non-zero pool->tx_metadata_len can cause negative integer overflow. Both scenarios can then pass the validation successfully. This doesn't happen with valid XSk applications, but can be used to perform attacks.
Always promote desc->len to ``u64`` first to exclude positive overflows of it. Use explicit check_{add,sub}_overflow() when validating desc->addr (which is ``u64`` already).
bloat-o-meter reports a little growth of the code size:
add/remove: 0/0 grow/shrink: 2/1 up/down: 60/-16 (44) Function old new delta xskq_cons_peek_desc 299 330 +31 xsk_tx_peek_release_desc_batch 973 1002 +29 xsk_generic_xmit 3148 3132 -16
but hopefully this doesn't hurt the performance much.
Which versions are affected by CVE-2025-40159?
How do I fix CVE-2025-40159?
Apply the vendor's patch.
Is CVE-2025-40159 being exploited?
There is no known exploitation of CVE-2025-40159 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40159, DEBIAN-CVE-2025-40159, GHSA-9mvj-23j7-q46q, ROOT-OS-UBUNTU-2404-CVE-2025-40159, UBUNTU-CVE-2025-40159.