Bug 2507729 (CVE-2026-64552)

Summary: CVE-2026-64552 kernel: virtio-net: fix len check in receive_big()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's virtio-net component. A malicious virtio backend can exploit an insufficient length check in the `receive_big()` function, leading to an out-of-bounds write. This vulnerability can result in a denial of service (DoS) due to system instability or crashes.
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Description OSIDB Bzimport 2026-07-27 21:01:58 UTC 
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.
Comment 1 TEJ RATHI 2026-07-29 05:21:12 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072737-CVE-2026-64552-5e13@gregkh/T