CVE-2026-72493

CVE CVE-2026-72493EUVD EUVD-2026-59392Published 2026-08-15T05:57:27.000ZLast changed 2026-08-17T05:44:54.000ZCVSS 9.9

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: net: serialize netif_running() check in enqueue_to_backlog() Syzbot reported a KASAN slab-use-after-free in fib_rules_lookup(). The root cause is a race condition where packets can escape the backlog flushing during device unregistration (e.g., during netns exit). Commit e9e4dd3267d0 ("net: do not process device backlog during unregistration") introduced a lockless netif_running() check in enqueue_to_backlog() to prevent queuing packets to an unregistering device. However, this creates a TOCTOU race window. A lockless transmitter (like veth_xmit) can pass the check before dev_close() clears IFF_UP. If the transmitter is then delayed, flush_all_backlogs() can run and finish before the transmitter grabs the backlog lock and queues the packet. The packet then escapes the flush and triggers UAF later when processed. Fix this by moving the netif_running() check inside the backlog lock. This serializes the check with the flush work (which also grabs the lock). We then either queue the packet before the flush runs (so it gets flushed), or check netif_running() after the flush/close completes (so it gets dropped).

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux 3.12.48 <3.13; f6533fed1bfa842e391ee50f9a9c5e963c71e579; b5d73d9cdd6be22795499890ea928a6f57ef829c; e9e4dd3267d0c5234c5c0f47440456b10875dec9 <2fface6e0bbd6314d1d9d071abf2c4d67548511c; e9e4dd3267d0c5234c5c0f47440456b10875dec9 <46762cefe7f4e5bffc1eb467810a7bbb02e461d7; 3.18.22 <3.19; f1fdb184aefa8447560e3ea0e605171592ffee41; 2095ab2456da766174cda8bc105d7a7b1bc70e16; f75c8a3015422128ca150e81c730bc2a471b5f4a; 78b6803a1961369d0b8350ff1f99b7375bbd7a8f; 4.2; patch: 7.2; 3.14.54 <3.15; 4.1.9 <4.2; 3.2.71 <3.3; patch: 0; patch: 7.1.5; 3.4.111 <3.5

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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