CVE-2026-72493Critical· 9.9▾ Midnight

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 whe…

▾ Midnight zone — Critical, or high with PoC / in-the-wild

Depth score55/ 100 · Moderate

impact 54.5 · likelihood 0.1 · exploitation 0

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Proof of concept

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Published

Aug 15, 2026

Updated

Oct 15, 2026

CVSS

9.9

Vendor

Linux

Product

Linux

CWE

—

Depth score

55 · Moderate

EPSS

0.40% · p34

Platforms

—

Source

NVD

Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CISA SSVC

decided 2026-10-16

Exploitation: none
Automatable: no
Technical impact: total

Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.

EPSS history

Exploit-prediction probability, daily snapshots since Oct 15.

0.3% → 0.4%▲ 0.05%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

4 events · 69 days

Aug 15, 2026Published
Disclosed via NVD
Oct 15, 2026Record revised
Last analysed / modified upstream
Oct 15, 2026EPSS first tracked
0.3%
Oct 23, 2026EPSS peak
0.3% → 0.4%

Linux #nvd #cve.org

Affected

Linux >= e9e4dd3267d0c5234c5c0f47440456b10875dec9 < b422e3eff0edf0975de4883929adbed28f9d08bc
Linux >= e9e4dd3267d0c5234c5c0f47440456b10875dec9 < 2fface6e0bbd6314d1d9d071abf2c4d67548511c
Linux >= e9e4dd3267d0c5234c5c0f47440456b10875dec9 < 46762cefe7f4e5bffc1eb467810a7bbb02e461d7
Linux 78b6803a1961369d0b8350ff1f99b7375bbd7a8f
Linux b5d73d9cdd6be22795499890ea928a6f57ef829c
Linux f6533fed1bfa842e391ee50f9a9c5e963c71e579
Linux 2095ab2456da766174cda8bc105d7a7b1bc70e16
Linux f1fdb184aefa8447560e3ea0e605171592ffee41
Linux f75c8a3015422128ca150e81c730bc2a471b5f4a
Linux >= 3.2.71 < 3.3
Linux >= 3.4.111 < 3.5
Linux >= 3.12.48 < 3.13
Linux >= 3.14.54 < 3.15
Linux >= 3.18.22 < 3.19
Linux >= 4.1.9 < 4.2
Linux 4.2

Full technical detail▾

Overview

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).

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

References

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#nvd#cve.org