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CVE-2026-53088
net: bcmgenet: fix off-by-one in bcmgenet_put_txcb
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-2026-53088 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 write_ptr points to the next open tx_cb. We want to return the tx_cb that gets rewinded, so we must rewind the pointer first then return the tx_cb that it points to. That way the txcb can be correctly cleaned up.
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
- 0.40%, higher than 32.6% 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 |
|---|---|---|
| 4.13 | 5.10.258 | 14e9f86564ff |
| 4.13 | 5.15.209 | fb9a3c1f547d |
| 4.13 | 6.1.175 | 85f34ec320d3 |
| 4.13 | 6.6.141 | 2a7459017042 |
| 4.13 | 6.12.91 | 29394f722f62 |
| 4.13 | 6.18.33 | 4cab761fc51c |
| 4.13 | 7.0.10 | 72df896e31dd |
| 4.13 | 7.1 | 57f3f53d2c9c |
| 3.16.50 | 0 | 0 |
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 |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | 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 bcmgenet Ethernet transmit path, reachable when a network-facing embedded/router system sends replies or forwards attacker-supplied traffic through the affected interface.
- AC:LAttack complexity, low
- The off-by-one cleanup is deterministic once the transmit error/reclaim path is reached, and an attacker can repeatedly drive transmit activity and resource pressure without needing to win an uncontrolled race.
- PR:NPrivileges required, none
- No authentication or local account is required in the highest-impact network-facing deployment, because unauthenticated network traffic can cause packets to be transmitted through the driver.
- UI:NUser interaction, none
- Exploitation does not require a victim user to open a file, mount media, or perform any other interactive action.
- S:UScope, unchanged
- The impact remains within the kernel and the affected host's networking/DMA resources, without crossing a separate security authority such as a VM boundary.
- C:HConfidentiality impact, high
- The wrong transmit control block can leave stale skb/DMA metadata and later operate on dangling kernel objects, making kernel memory disclosure a defensible worst-case outcome.
- I:HIntegrity impact, high
- The stale control-block cleanup can plausibly become double-free or use-after-free style kernel heap corruption, which is treated as high integrity impact.
- A:HAvailability impact, high
- Even without full exploitation, incorrect cleanup of transmit control blocks and DMA mappings can corrupt driver state, leak resources, or crash/hang networking/kernel execution.