CVE-2026-72493
net: serialize netif_running() check in enqueue_to_backlog()
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).
INFO
Published Date :
Aug. 15, 2026, 6:22 a.m.
Last Modified :
Aug. 17, 2026, 6:19 a.m.
Remotely Exploit :
Yes !
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Move netif_running() check inside backlog lock.
- Queue packets before flush or drop if device is closed.
- Apply the kernel patch for net: serialize netif_running().
- Update the Linux kernel to the fixed version.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-72493.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/2fface6e0bbd6314d1d9d071abf2c4d67548511c | |
| https://git.kernel.org/stable/c/46762cefe7f4e5bffc1eb467810a7bbb02e461d7 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-72493 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-72493
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-72493 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-72493 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'e9e4dd3267d0c5234c5c0f47440456b10875dec9', 'lessThan': '2fface6e0bbd6314d1d9d071abf2c4d67548511c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9e4dd3267d0c5234c5c0f47440456b10875dec9', 'lessThan': '46762cefe7f4e5bffc1eb467810a7bbb02e461d7', 'versionType': 'git'}, {'status': 'affected', 'version': '78b6803a1961369d0b8350ff1f99b7375bbd7a8f', 'versionType': 'git'}, {'status': 'affected', 'version': 'b5d73d9cdd6be22795499890ea928a6f57ef829c', 'versionType': 'git'}, {'status': 'affected', 'version': 'f6533fed1bfa842e391ee50f9a9c5e963c71e579', 'versionType': 'git'}, {'status': 'affected', 'version': '2095ab2456da766174cda8bc105d7a7b1bc70e16', 'versionType': 'git'}, {'status': 'affected', 'version': 'f1fdb184aefa8447560e3ea0e605171592ffee41', 'versionType': 'git'}, {'status': 'affected', 'version': 'f75c8a3015422128ca150e81c730bc2a471b5f4a', 'versionType': 'git'}, {'status': 'affected', 'version': '3.2.71', 'lessThan': '3.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.111', 'lessThan': '3.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.12.48', 'lessThan': '3.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.14.54', 'lessThan': '3.15', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.18.22', 'lessThan': '3.19', 'versionType': 'semver'}, {'status': 'affected', 'version': '4.1.9', 'lessThan': '4.2', 'versionType': 'semver'}], 'programFiles': ['net/core/dev.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4.2'}, {'status': 'unaffected', 'version': '0', 'lessThan': '4.2', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/core/dev.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'e9e4dd3267d0c5234c5c0f47440456b10875dec9', 'lessThan': '2fface6e0bbd6314d1d9d071abf2c4d67548511c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9e4dd3267d0c5234c5c0f47440456b10875dec9', 'lessThan': '46762cefe7f4e5bffc1eb467810a7bbb02e461d7', 'versionType': 'git'}, {'status': 'affected', 'version': '78b6803a1961369d0b8350ff1f99b7375bbd7a8f', 'versionType': 'git'}, {'status': 'affected', 'version': 'b5d73d9cdd6be22795499890ea928a6f57ef829c', 'versionType': 'git'}, {'status': 'affected', 'version': 'f6533fed1bfa842e391ee50f9a9c5e963c71e579', 'versionType': 'git'}, {'status': 'affected', 'version': '2095ab2456da766174cda8bc105d7a7b1bc70e16', 'versionType': 'git'}, {'status': 'affected', 'version': 'f1fdb184aefa8447560e3ea0e605171592ffee41', 'versionType': 'git'}, {'status': 'affected', 'version': 'f75c8a3015422128ca150e81c730bc2a471b5f4a', 'versionType': 'git'}, {'status': 'affected', 'version': '3.2.71', 'lessThan': '3.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.111', 'lessThan': '3.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.12.48', 'lessThan': '3.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.14.54', 'lessThan': '3.15', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.18.22', 'lessThan': '3.19', 'versionType': 'semver'}, {'status': 'affected', 'version': '4.1.9', 'lessThan': '4.2', 'versionType': 'semver'}], 'programFiles': ['net/core/dev.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4.2'}, {'status': 'unaffected', 'version': '0', 'lessThan': '4.2', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/core/dev.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'e9e4dd3267d0c5234c5c0f47440456b10875dec9', 'lessThan': '2fface6e0bbd6314d1d9d071abf2c4d67548511c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9e4dd3267d0c5234c5c0f47440456b10875dec9', 'lessThan': '46762cefe7f4e5bffc1eb467810a7bbb02e461d7', 'versionType': 'git'}, {'status': 'affected', 'version': '78b6803a1961369d0b8350ff1f99b7375bbd7a8f', 'versionType': 'git'}, {'status': 'affected', 'version': 'b5d73d9cdd6be22795499890ea928a6f57ef829c', 'versionType': 'git'}, {'status': 'affected', 'version': 'f6533fed1bfa842e391ee50f9a9c5e963c71e579', 'versionType': 'git'}, {'status': 'affected', 'version': '2095ab2456da766174cda8bc105d7a7b1bc70e16', 'versionType': 'git'}, {'status': 'affected', 'version': 'f1fdb184aefa8447560e3ea0e605171592ffee41', 'versionType': 'git'}, {'status': 'affected', 'version': 'f75c8a3015422128ca150e81c730bc2a471b5f4a', 'versionType': 'git'}, {'status': 'affected', 'version': '3.2.71', 'lessThan': '3.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.111', 'lessThan': '3.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.12.48', 'lessThan': '3.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.14.54', 'lessThan': '3.15', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.18.22', 'lessThan': '3.19', 'versionType': 'semver'}, {'status': 'affected', 'version': '4.1.9', 'lessThan': '4.2', 'versionType': 'semver'}], 'programFiles': ['net/core/dev.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4.2'}, {'status': 'unaffected', 'version': '0', 'lessThan': '4.2', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/core/dev.c'], 'defaultStatus': 'affected'}] Added 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). Added Reference https://git.kernel.org/stable/c/2fface6e0bbd6314d1d9d071abf2c4d67548511c Added Reference https://git.kernel.org/stable/c/46762cefe7f4e5bffc1eb467810a7bbb02e461d7