# CVE-2026-72493: net: serialize netif_running() check in enqueue_to_backlog()

CVE-2026-72493 is fixed in 54 products on 1 platform, first by DEBIAN-CVE-2026-72493, released August 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-72493
- Priority: High
- CVSS: 9.9 (Moderate)
- EPSS: 0.0040
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 15, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72493

## Description

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).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | bpftool6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | bpftool6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | dtb-aarch64 opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-64kb opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-64kb sles 15.7 | 6.4.0-150700.53.87.3 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-64kb sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-azure opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-azure sles 15.7 | 6.4.0-150700.53.87.3 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-azure sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-default opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-default sles 15.6 | 6.4.0-150600.23.143.1 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-default sles 15.7 | 6.4.0-150700.53.87.3 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-default sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base opensuse-leap 16.0 | 6.12.0-160000.40.1.160000.2.29 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base sles 15.6 | 6.4.0-150600.23.143.1.150600.12.66.3 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base sles 15.7 | 6.4.0-150700.53.87.3.150700.17.49.2 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-default-base sles 16.0 | 6.12.0-160000.40.1.160000.2.29 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-docs opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-docs sles 15.6 | 6.4.0-150600.23.143.1 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-docs sles 15.7 | 6.4.0-150700.53.87.3 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-docs sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-kvmsmall opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-6.12.110-135.201 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-6.18.51-120.162 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-SLE15-SP6_Update_33 sles 15.6 | 1-150600.13.5.1 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-SLE15-SP7-RT_Update_22 sles 15.7 | 1-150700.1.3.1 | [SUSE-SU-2026:4940-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4940-1.md) | Nov 7, 2026 |
| Linux | kernel-livepatch-SLE15-SP7_Update_23 sles 15.7 | 1-150700.15.3.2 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-build opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-build sles 15.6 | 6.4.0-150600.23.143.1 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-build sles 15.7 | 6.4.0-150700.53.87.2 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-qa opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-rt opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-source opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-source sles 15.6 | 6.4.0-150600.23.143.1 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-source sles 15.7 | 6.4.0-150700.53.87.3 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-source sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-syms opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-syms sles 15.6 | 6.4.0-150600.23.143.1 | [SUSE-SU-2026:4934-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4934-1.md) | Nov 7, 2026 |
| Linux | kernel-syms sles 15.7 | 6.4.0-150700.53.87.1 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-syms sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel-zfcpdump opensuse-leap 16.0 | 6.12.0-160000.40.1 | [OPENSUSE-SU-2026:22167-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22167-1.md) | Nov 7, 2026 |
| Linux | kernel-zfcpdump sles 15.7 | 6.4.0-150700.53.87.3 | [SUSE-SU-2026:4935-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4935-1.md) | Nov 7, 2026 |
| Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.40.1 | [SUSE-SU-2026:24446-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24446-1.md) | Nov 7, 2026 |
| Linux | kernel6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-devel amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-headers amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-tools amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | kernel6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-devel amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-headers amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-tools amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-72493](https://patchblox.com/security/data/fix/linux/debian-cve-2026-72493.md) | Aug 15, 2026 |
| Linux | linux Debian 14 | 7.1.5-1 | [DEBIAN-CVE-2026-72493](https://patchblox.com/security/data/fix/linux/debian-cve-2026-72493.md) | Aug 15, 2026 |
| Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | perf6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | perf6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | python3-perf6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 |
| Linux | python3-perf6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |
| Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 |

---

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