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CVE-2026-64056
net: ethernet: cortina: Make RX SKB per-port
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-64056 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 | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed 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 | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The SKB used to assemble packets from fragments in gmac_rx() is static local, but the Gemini has two ethernet ports, meaning there can be races between the ports on a bad day if a device is using both. Make the RX SKB a per-port variable and carry it over between invocations in the port struct instead. Zero the pointer once we call napi_gro_frags(), on error (after calling napi_free_frags()) or if the port is stopped. Zero it in some place where not strictly necessary just to emphasize what is going on. This was found by Sashiko during normal patch review.
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/cortina/gemini.c
- What this is
- ARM/CORTINA SYSTEMS GEMINI ARM ARCHITECTUREMAINTAINERS section matched on drivers/net/ethernet/cortina/ · linux-arm-kernel@lists.infradead.org · Maintained
- Kernel module
- none to look for. The file would have gone into gemini, and Debian does not compile it into that module, so finding gemini in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_ETHERNET|CONFIG_GEMINI_ETHERNET|CONFIG_NET_VENDOR_CORTINA' /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 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_ETHERNET, CONFIG_GEMINI_ETHERNET, CONFIG_NET_VENDOR_CORTINA
- 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
- 2026-07-19 (3 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
- 0.55%, higher than 44.9% 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 |
|---|---|---|
| 4.16 | 5.10.258 | 27856d533eca |
| 4.16 | 5.15.209 | b6b22824b30e |
| 4.16 | 6.1.175 | 6bba24e9ebe6 |
| 4.16 | 6.6.142 | 3b249988d774 |
| 4.16 | 6.12.92 | 72158ea185b2 |
| 4.16 | 6.18.34 | cfd62907f3cd |
| 4.16 | 7.0.11 | 67a35e7da7ef |
| 4.16 | 7.1 | 06937db21ee3 |
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 code runs in the netdev RX path (gmac_irq → napi_schedule → gmac_napi_poll → gmac_rx) when Ethernet frames are DMA'd from the wire, so any remote host that can send packets to a reachable Gemini GMAC interface can trigger it.
- AC:LAttack complexity, low
- An attacker controls both sides of the race by flooding one or both GMAC ports with multi-descriptor/jumbo frames to keep skb assembly in progress while concurrent NAPI polls run on the independent per-port IRQ handlers without serialization on the shared static skb pointer.
- PR:NPrivileges required, none
- Exploitation requires only the ability to deliver Ethernet frames to an active interface; there are no authentication gates, capability checks, or local syscalls on the RX path from hardware interrupt through gmac_rx().
- UI:NUser interaction, none
- Triggering the race requires only crafted or high-volume network traffic; no victim interaction such as mounting a filesystem or opening a file is needed.
- S:UScope, unchanged
- The corruption is confined to kernel networking state (shared skb assembly between the two GMAC ports on the same host); impact does not cross a VM, IOMMU, or sandbox security boundary.
- C:HConfidentiality impact, high
- Concurrent corruption of a shared skb and mismatched napi_get_frags/napi_gro_frags/napi_free_frags usage across ports can cause use-after-free and skb metadata corruption that enables arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Cross-port skb corruption via concurrent skb_fill_page_desc and len updates, plus orphaned or double-freed skb/page state, provides memory corruption primitives that can be leveraged for arbitrary kernel writes or code execution.
- A:HAvailability impact, high
- The race can cause kernel oopses or panics from slab/list corruption, invalid page refcount handling, or crashes inside napi_gro_frags when skb state is corrupted across the two ports.