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CVE-2026-72411
net: dsa: mxl862xx: fix use-after-free of DSA ports in crc_err_work
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72411 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Upon an MDIO CRC error mxl862xx_crc_err_work_fn() walks the DSA ports and closes the CPU port conduits: dsa_switch_for_each_cpu_port(dp, priv->ds) dev_close(dp->conduit); mxl862xx_remove() unregisters the switch before cancelling this work: set_bit(MXL862XX_FLAG_WORK_STOPPED, &priv->flags); cancel_delayed_work_sync(&priv->stats_work); dsa_unregister_switch(ds); mxl862xx_host_shutdown(priv); dsa_unregister_switch() frees the dsa_port objects. If a CRC error schedules the work during teardown it can run after the ports have been freed and dereference freed memory. Guard the port walk with MXL862XX_FLAG_WORK_STOPPED, which is already set before dsa_unregister_switch(). DSA tears the ports down under rtnl_lock(), so checking the flag under rtnl_lock() means the work either runs before teardown and sees valid ports, or runs afterwards, observes the flag and skips the walk. This mirrors the host_flood_work handler, which skips torn-down ports under rtnl_lock().
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/dsa/mxl862xx/mxl862xx-host.c
- What this is
- MAXLINEAR MXL862XX SWITCH DRIVERMAINTAINERS section matched on drivers/net/dsa/mxl862xx/ · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_NET_DSA|CONFIG_NET_DSA_MXL862' /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.
Show whether Debian builds this, per release
Debian does not build this code in 2 releases. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidn
- ?
- not established - no Makefile entry for the affected file
- n
- not enabled on any flavour - this release does not build the code
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_NET_DSA, CONFIG_NET_DSA_MXL862
- 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
- 2026-08-15 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- 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 |
|---|---|---|
| 7.1 | 7.1.5 | cf52622fbc27 |
| 7.1 | 7.2 | bcb3b8314611 |
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:LAttack vector, local
- The UAF is in mxl862xx_remove() racing crc_err_work; reachable only via local MDIO driver teardown (module unload, sysfs unbind) after MDIO CRC errors on the on-board management bus, not from remote network packet handling.
- AC:LAttack complexity, low
- An attacker controls the teardown side via repeated sysfs unbind/rmmod while crc_err_work is armed by automatic 2s stats polling or MDIO CRC failures during cancel_delayed_work_sync; both race sides are repeatable without uncontrollable conditions.
- PR:LPrivileges required, low
- Per kernel CNA precedent for driver remove-path work-item UAFs, PR:L applies: crc_err_work is queued autonomously by kernel MDIO/stats paths without elevated capability, and a local user can drive removal via sysfs unbind or module unload.
- UI:NUser interaction, none
- No victim interaction is required; crc_err_work is scheduled by automatic kernel MDIO activity and the UAF occurs when driver teardown frees dsa_port objects before the still-pending workqueue handler runs.
- S:UScope, unchanged
- Corruption is confined to kernel heap objects (freed dsa_port and net_device) within the same kernel security authority, with no VM, IOMMU, or namespace boundary crossed.
- C:HConfidentiality impact, high
- mxl862xx_crc_err_work_fn() walks freed dsa_port structures and reads dp->conduit from reclaimed slab memory before dev_close(), yielding sprayable arbitrary kernel memory disclosure per UAF guidance.
- I:HIntegrity impact, high
- dev_close() on a dangling net_device* dereferences netdev ops and mutates device state through pointers read from freed dsa_port memory, providing control-flow hijack and arbitrary write primitives after heap grooming.
- A:HAvailability impact, high
- The use-after-free dereference of freed dsa_port/net_device during dev_close() causes a kernel oops or panic even without deliberate exploitation, repeatable by cycling driver removal against pending crc_err_work.