TI-2026-50772 Aliases CVE-2026-72493 GHSA-hhj5-7x2f-mw3r

net: serialize netif_running() check in enqueue_to_backlog()

MEDIUM 43Published 2026-08-15 · Updated 2026-10-21

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: High · High · High
Fix status: Partial Red Hat: 5 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

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).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00403 34th percentileScored 2026-11-07

Fix Partial Linux (Linux): 3.3, 3.5, 3.13 +7Red Hat: 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Linux	Linux	3.2.71 to before 3.3; 3.4.111 to before 3.5; 3.12.48 to before 3.13; 3.14.54 to before 3.15; 3.18.22 to before 3.19; 4.1.9 to before 4.2	3.3, 3.5, 3.13, 3.15, 3.19, 4.2	Patch available	CNA
Linux	Linux	4.2 and later	6.12.114, 6.18.57, 7.1.5, 7.2	Patch available	CNA

Linux VendorLinux Affected 3.2.71 to before 3.3; 3.4.111 to before 3.5; 3.12.48 to before 3.13; 3.14.54 to before 3.15; 3.18.22 to before 3.19; 4.1.9 to before 4.2 Fixed in 3.3, 3.5, 3.13, 3.15, 3.19, 4.2 Patch available CNA
Linux VendorLinux Affected 4.2 and later Fixed in 6.12.114, 6.18.57, 7.1.5, 7.2 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:o:linux:linux_kernel::::::::	—	—	Linux

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Fix · CNA Linux (Linux) Fixed in 3.3, 3.5, 3.13, 3.15, 3.19, 4.2
Fix · CNA Linux (Linux) Fixed in 6.12.114, 6.18.57, 7.1.5, 7.2

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 10	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 6	Affected	No fix planned: Out of support scope
Red Hat Enterprise Linux 7	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-72493
2026-10-03 Alias added: GHSA-hhj5-7x2f-mw3r
2026-10-16 Fix available: Linux/[email protected], Linux/Linux@b422e3eff0edf0975de4883929adbed28f9d08bc · CNA
2026-10-16 1 new reference · CNA
2026-10-16 CISA SSVC decision points changed
2026-10-21 Fix available: Linux/[email protected], Linux/Linux@cbe10ea090ea9d6fa5ff50c9b44f2a86fe56f0b7 · CNA
2026-10-21 1 new reference · CNA

References

Other 4

TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4

See all 21741 →

Sources

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