CVE-2026-74612 veth: fix skb length accounting after XDP frag adjustment
A Linux kernel veth driver flaw allows attackers to read kernel memory and cause crashes via crafted UDP packets with XDP adjustments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74612?
CVE-2026-74612 is a critical vulnerability in Linux, published on 22 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
veth: fix skb length accounting after XDP frag adjustment
veth exposes non-linear skb fragments through an xdp_buff. If an XDP program adjusts the fragment area, veth_xdp_rcv_skb() copies xdp_frags_size back to skb->data_len but leaves skb->len containing the old fragment contribution.
After a fragment shrink, this makes skb_headlen() larger than the actual linear area. In the reproduced UDP receive path, __skb_datagram_iter() copied 1024 bytes past the actual linear tail to userspace, starting at struct skb_shared_info. The copied bytes included the affected skb's nr_frags, xdp_frags_size, and a kernel pointer from skb_shinfo(skb)->frags[0]. Real packet data was displaced by the same amount and truncated at the end.
Subtract the old data_len before replacing it and add the new data_len afterwards, keeping skb->len and skb->data_len synchronized.
Additionally, bpf_xdp_pull_data() can advance data_end while leaving frags present. The skb is then still non-linear, so the old __skb_put(skb, off) triggers SKB_LINEAR_ASSERT().
Use skb_set_tail_pointer() and update skb->len explicitly instead, following bpf_prog_run_generic_xdp(). Unlike __skb_put(), skb_set_tail_pointer() does not require a linear skb.
A 60000-byte UDP datagram on a veth pair with MTU 64000 was shortened by 1024 bytes from its fragment area. Before the fix, all 10 runs produced corrupted payloads. After the fix, all 10 runs matched the expected payload exactly. A forced-tailroom reproducer also exercises bpf_xdp_pull_data() with frags still present; the old code triggers SKB_LINEAR_ASSERT(), while this fix passes 10/10 runs.
Which versions are affected by CVE-2026-74612?
Linux distribution packages (6)
kernel-livepatch-SLE15-SP7-RT_Update_20 SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 2-150700.2.1 |
kernel-livepatch-SLE15-SP7_Update_21 SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 2-150700.2.1 |
kernel-livepatch-MICRO-6-0-RT_Update_29 SUSE:Linux Micro 6.0 | All versions | 2-1.1 |
kernel-livepatch-MICRO-6-0_Update_29 SUSE:Linux Micro 6.0 | All versions | 2-1.1 |
kernel-livepatch-MICRO-6-0-RT_Update_29 SUSE:Linux Micro 6.1 | All versions | 2-1.1 |
kernel-livepatch-MICRO-6-0_Update_29 SUSE:Linux Micro 6.1 | All versions | 2-1.1 |
How do I fix CVE-2026-74612?
Apply the vendor's patch.
Is CVE-2026-74612 being exploited?
There is no known exploitation of CVE-2026-74612 in the wild and no public exploit code.
Sources
Also known as AZL-97053, BELL-CVE-2026-74612, DEBIAN-CVE-2026-74612, GHSA-pg5f-gw23-248r, SUSE-SU-2026:24021-1, SUSE-SU-2026:24039-1 and 5 more.