CVE-2026-74478 Affecting linux-6.12 package, versions <6.12.107-1~deb12u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.57% (45th percentile)

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  • Snyk IDSNYK-ECHOLATEST-LINUX612-19964168
  • published20 Sept 2026
  • disclosed15 Aug 2026

Introduced: 15 Aug 2026

CVE-2026-74478  (opens in a new tab)

How to fix?

Upgrade Echo:latest linux-6.12 to version 6.12.107-1~deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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 &lt; 0) {
    dev_kfree_skb_irq(skb);
    vp-&gt;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.

CVSS Base Scores

version 3.1