CVE-2026-74476
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.
CSIRTS triage
- What
- The veth driver does not properly convert fragmented packet lists before running XDP programs.
- Who is affected
- Systems running Linux kernel with veth virtual network interfaces and XDP in use.
- Urgency
- Medium priority; denial-of-service risk with CVSS 4.1 and no active exploitation.
- Action
- Apply Linux kernel patch addressing CVE-2026-74476 when available.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.49% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 40% of all EPSS-scored CVEs.
Advisory coverage (2)
- criticalCVE-2026-74476: In the Linux kernel, the following vulnerability has been resolved: veth: convert frag_list sk…nvd · 2026-08-15
- mediumCVE-2026-74476: veth: convert frag_list skbs before running XDPmsrc · 2026-08-11
External references
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