CVE-2026-64552: virtio-net: fix len check in receive_big()

Severity: high (CVSS 8.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-27 · updated 2026-10-19
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: virtio-net: fix len check in receive_big() receive_big() bounds the device-announced length by (big_packets_num_skbfrags + 1) * PAGE_SIZE. That is still too loose: add_recvbuf_big() sets sg[1] to start at offset sizeof(struct padded_vnet_hdr) into the first page, so the chain actually carries hdr_len + (PAGE_SIZE - sizeof(padded_vnet_hdr)) + big_packets_num_skbfrags * PAGE_SIZE bytes -- 20 bytes less than the check allows for the common hdr_len == 12 case. A malicious virtio backend can announce a len in that gap. page_to_skb() then walks one frag past the page chain, storing a NULL page->private into skb_shinfo()->frags[MAX_SKB_FRAGS], which is both an out-of-bounds write past the static frag array and a NULL frag handed up the rx path. Bound len by the size add_recvbuf_big() actually advertised.

Affected products

Linux kernel: from 6.1.159 before 6.1.178; from 6.6.117 before 6.6.145; from 6.12.58 before 6.12.97; from 6.17.8 before 6.18; 6.18 — fixed in 6.1.178, 6.12.97, 6.18, 6.6.145, 7.2

How to fix

Upgrade to a fixed version: Linux kernel 6.1.178, 6.12.97, 6.18, 6.6.145. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-64552 or the next vulnerability affects your stack