CVE-2026-74478

In the Linux kernel, the following vulnerability has been resolved: um: vector: fix use-after-free in vector_mmsg_rx() When vector_mmsg_rx() discards a packet whose overlay header fails verify_header(), it frees the skb and continues the loop: if (header_check < 0) { dev_kfree_skb_irq(skb); vp->estats.rx_encaps_errors++; continue; } The normal and short-packet paths fall through to the bottom of the loop body, which clears the consumed slot and advances the cursors: (*skbuff_vector) = NULL; mmsg_vector++; skbuff_vector++; The verify_header() < 0 path skips that via continue, so the freed skb is left in skbuff_vector[] and the cursors do not advance. The next iteration reads the same slot, gets the freed skb, and frees it again, producing a refcount underflow / use-after-free in the RX path. Discard the slot the same way the other paths do before continuing. Only transports whose verify_header() can return negative are affected: GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not), so any peer on such a transport can trigger it without authentication.

Affected products

Kernel, Linux, Linux-Allwinner-5.19, Linux-Aws, Linux-Aws-5.0, Linux-Aws-5.11, Linux-Aws-5.13, Linux-Aws-5.15

CVSS 3.1

9.8 CRITICAL

EPSS

0.6% (45th percentile)

NVD status

Received

Published

2026-08-15

No exploit for CVE-2026-74478 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.