CVE-2026-72493: net: serialize netif_running() check in enqueue_to_backlog()
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.4%
EPSS score, percentile 34.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.9 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- from 3.2.71 to before 3.3
- from 3.4.111 to before 3.5
- 4.2
Unaffected before 4.2; 6.12.114; 6.18.57; 7.1.5; 7.2
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from e9e4dd3267d0 to before cbe10ea090ea |
| Affected | from e9e4dd3267d0 to before b422e3eff0ed |
| Affected | from e9e4dd3267d0 to before 2fface6e0bbd |
| Affected | from e9e4dd3267d0 to before 46762cefe7f4 |
| Affected | 78b6803a1961 |
| Affected | b5d73d9cdd6b |
| Affected | f6533fed1bfa |
| Affected | 2095ab2456da |
| Affected | f1fdb184aefa |
| Affected | f75c8a301542 |
| Affected | from 3.2.71 to before 3.3 |
| Affected | from 3.4.111 to before 3.5 |
Versions not listed are: unaffected.
And 4 more version entries in the CVE record.
| Status | Versions |
|---|---|
| Affected | 4.2 |
| Unaffected | before 4.2 |
| Unaffected | 6.12.114 |
| Unaffected | 6.18.57 |
| Unaffected | 7.1.5 |
| Unaffected | 7.2 |
Versions not listed are: affected.
Versions the record lists as unaffected: 6.12.114, 6.18.57, 7.1.5, 7.2.
Source: CVE List, as of . About the data.
About this vulnerability
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 durin…
Summary: CVE record, as of .
- CISA has not added CVE-2026-72493 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 15 Aug 2026.
- The CVE record carries a CVSS v3.1 base score of 9.9 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.4% (percentile 34.5), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact total.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
net: serialize netif_running() check in enqueue_to_backlog()
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: CVE List, as of . About the data.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
Known exploited Linux vulnerabilities
- CVE-2026-46300: Linux Kernel Missing Initialization of a Variable Vulnerability
- CVE-2025-39682: Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
- CVE-2025-39964: Linux Kernel Race Condition Vulnerability
- CVE-2026-53266: Linux Kernel Out-of-Bounds Write Vulnerability
- CVE-2026-53362: Linux Kernel Unspecified Vulnerability