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CVE-2026-53086
net: bcmgenet: fix racing timeout handler
Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53086 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The bcmgenet_timeout handler tries to take down all tx queues when a single queue times out. This is over zealous and causes many race conditions with queues that are still chugging along. Instead lets only restart the timed out queue.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/ethernet/broadcom/genet/bcmgenet.c
- What this is
- BROADCOM GENET ETHERNET DRIVERMAINTAINERS section matched on drivers/net/ethernet/broadcom/genet/ · netdev@vger.kernel.org · Maintained
- Kernel module
- genet
Check it on the machine
grep -wE 'CONFIG_BCMGENET|CONFIG_ETHERNET|CONFIG_NET_VENDOR_BROADCOM' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w genetPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_BCMGENET, CONFIG_ETHERNET, CONFIG_NET_VENDOR_BROADCOM
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-06-24 (4 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.30%, higher than 21.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.2 | 6.1.175 | e85b0c0a12e9 |
| 4.2 | 6.6.141 | e8206538cbaf |
| 4.2 | 6.12.91 | 681fdfe823b4 |
| 4.2 | 6.18.33 | c270e2bec3e5 |
| 4.2 | 7.0.10 | 7ce1c26aac3b |
| 4.2 | 7.1 | 5393b2b5bee2 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The vulnerable path is the Ethernet TX path and `ndo_tx_timeout` recovery for a network interface; a remote peer can cause the affected host or router to transmit traffic through bcmgenet without local code execution. In an internet-facing or routed embedded deployment, this is reachable via network traffic.
- AC:LAttack complexity, low
- The race is between timeout recovery on one TX queue and other active TX queues, and an attacker can plausibly create sustained concurrent traffic to exercise multiple queues and keep the race repeatable. No special memory layout or victim interaction is required beyond traffic-induced queue activity.
- PR:NPrivileges required, none
- No kernel privilege check gates the watchdog timeout handler once the interface is up. A remote unauthenticated peer can trigger outbound responses or forwarded traffic in a reasonable deployment.
- UI:NUser interaction, none
- Exploitation does not require a user to open a file, mount anything, or take an interactive action. The vulnerable recovery runs asynchronously from normal network transmission and watchdog handling.
- S:UScope, unchanged
- The impact remains within the same host kernel and network device security authority. This is not a VM escape, IOMMU boundary bypass, or cross-scope sandbox escape.
- C:HConfidentiality impact, high
- The old handler reclaimed and freed in-flight SKBs/descriptors for queues that could still be transmitting, creating a DMA/use-after-free condition. Freed or reused kernel memory could plausibly be transmitted or otherwise exposed, so confidentiality is high.
- I:HIntegrity impact, high
- Freeing and reusing active TX control blocks while hardware still owns them is UAF-style memory corruption of kernel driver/DMA state. Under the required conservative scoring, this is treated as potentially enabling high-integrity impact rather than mere packet loss.
- A:HAvailability impact, high
- The race can corrupt TX ring accounting/state, trigger repeated TX watchdog failures, DMA/IOMMU faults, hangs, or kernel crashes. This is a high availability impact.