9.9

CVE-2026-72493: linux

CVSS: 9.9v3.1CriticalReceived
AliasesUBUNTU-CVE-2026-72493DEBIAN-CVE-2026-72493
Published 15-08-2026Last modified 16-10-2026
Open JSON

Vulnerability summary

CVE-2026-72493 is a critical (CVSS 9.9) vulnerability in linux. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 31.6% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.9/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.39%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 6 · Related 6
USN-8816-1USN-8816-2USN-8816-3USN-8816-4USN-8888-1USN-8888-2

Timeline

  1. 15-08-2026
    PublishedVulnerability first disclosed.
  2. 16-10-2026
    Last modifiedVulnerability information updated.

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).

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.39%

Chance of exploitation in the next 30 days

Percentile

32%

Versus all other CVEs

30-day change

+0.04 pp

From 0.35% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.39%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Ubuntu169 products
  • linuxAll versions (No fix recorded) | < 7.0.0-34.34
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 7.0.0-1013.13
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian1 product
  • linuxAll versions (No fix recorded) | < 7.1.5-1
Linux1 product
  • linux≥ e9e4dd3267d0c5234c5c0f47440456b10875dec9, < b422e3eff0edf0975de4883929adbed28f9d08bc | ≥ e9e4dd3267d0c5234c5c0f47440456b10875dec9, < 2fface6e0bbd6314d1d9d071abf2c4d67548511c | ≥ e9e4dd3267d0c5234c5c0f47440456b10875dec9, < 46762cefe7f4e5bffc1eb467810a7bbb02e461d7 | 78b6803a1961369d0b8350ff1f99b7375bbd7a8f | b5d73d9cdd6be22795499890ea928a6f57ef829c | f6533fed1bfa842e391ee50f9a9c5e963c71e579 | 2095ab2456da766174cda8bc105d7a7b1bc70e16 | f1fdb184aefa8447560e3ea0e605171592ffee41 | f75c8a3015422128ca150e81c730bc2a471b5f4a | ≥ 3.2.71, < 3.3 | ≥ 3.4.111, < 3.5 | ≥ 3.12.48, < 3.13 | ≥ 3.14.54, < 3.15 | ≥ 3.18.22, < 3.19 | ≥ 4.1.9, < 4.2 | 4.2

3 vendors · 171 products

References

13 links
Show all 13 references