Use-after-free in Linux bcmgenet driver when Tx queues are stopped
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Fixed
No CVSS vector from any source. Fix status from CNA.
Summary
The Linux kernel from 6.15 has a use-after-free flaw in the bcmgenet network driver, where the Tx queues are disabled before Tx NAPI is stopped. A completion running in between can wake the queue again, so a transmit can write to rings that were already freed. The source reports this from a KASAN log on a Raspberry Pi CM4, triggered by an MTU change while suspend froze user space.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: net: bcmgenet: stop Tx NAPI before disabling the queues bcmgenet_netif_stop() and the Wake-on-LAN branch of bcmgenet_suspend() both disable the Tx queues first and stop Tx NAPI several steps later. A completion in flight calls netif_tx_wake_queue() in between, and nothing stops the queue again, so a transmit can reach the rings after they have been freed. Close is safe because dev_deactivate_many() stops the qdisc first. bcmgenet_suspend() does not, so stop Tx NAPI before the queues on both paths. KASAN on a Raspberry Pi CM4, driven from an MTU change because suspend freezes user space before the callback runs: BUG: KASAN: use-after-free in bcmgenet_xmit+0x17f8/0x2258 Write of size 8 at addr ffffff8055844a68 by task ksoftirqd/0/14 bcmgenet_xmit+0x17f8/0x2258 dev_hard_start_xmit+0x13c/0x588 sch_direct_xmit+0x108/0x340 __dev_queue_xmit+0x1190/0x3848
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Update the Linux kernel to 6.18.55, 7.2.9 or 7.3, which contain the fix for the affected Linux kernel branches.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.18.55, 7.2.9, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 7 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98574
- 2026-10-18 Alias added: GHSA-rfvr-hxpg-f67j
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
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Sources
- CVE-2026-98574 · CVE Program
- CVE-2026-98574 · NVD
- FIRST EPSS
- GHSA-rfvr-hxpg-f67j · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98574 · Red Hat security data · CC BY 4.0
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