Bug 2516965 (CVE-2026-74476)

Summary: CVE-2026-74476 kernel: veth: convert frag_list skbs before running XDP
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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 veth component of the Linux kernel. This vulnerability occurs when a specially crafted network packet, known as a frag_list skb (socket buffer), is processed by the veth driver. An attacker could potentially send such a packet, causing the system to misinterpret fragment metadata. This misinterpretation can lead to a memory corruption issue, ultimately resulting in a system crash and a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-15 12:41:26 UTC 
In the Linux kernel, the following vulnerability has been resolved:

veth: convert frag_list skbs before running XDP

A frag_list skb can reach veth with data_len set but nr_frags zero.
veth_convert_skb_to_xdp_buff() only converts skbs that are shared,
locked, have frags[], or do not have enough headroom. It later uses
skb_is_nonlinear() to decide whether to set XDP_FLAGS_HAS_FRAGS and
xdp_frags_size.

That exposes frag_list data to XDP as if it were stored in frags[], but
frags[] is empty. AF_XDP copy mode can then trust the bogus XDP fragment
metadata, walk an empty fragment entry, and crash in memcpy() from
__xsk_rcv().

Route non-linear skbs through skb_pp_cow_data() before exposing them to
XDP, and only advertise XDP frags when the resulting skb has frags[].
skb_copy_bits() already handles frag_list input, and skb_pp_cow_data()
builds frags[] output with skb_add_rx_frag(), which is the
representation XDP multi-buffer expects.
Comment 1 gkamathe 2026-08-21 07:03:14 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081535-CVE-2026-74476-c830@gregkh/T