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CVE-2026-74707
xsk: validate metadata when processing requests
Published 2026-08-22 (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-2026-74707 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 | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The zero-copy path validates TX metadata while obtaining the descriptor context, then reads it again later when preparing the hardware request. User space can change the metadata between those operations and bypass the original validation. Validate the metadata in xsk_tx_metadata_request() and use the resulting flags snapshot for every feature check. Read request fields once so all zero-copy drivers process only values observed after successful validation.
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/intel/igc/igc_main.c
drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
include/net/libeth/xsk.h
include/net/xdp_sock_drv.h
net/xdp/xsk_buff_pool.c
- What this is
- INTEL ETHERNET DRIVERSMAINTAINERS section matched on drivers/net/ethernet/intel/*/ · intel-wired-lan@lists.osuosl.org · Maintained
- Kernel module
- igc
Check it on the machine
grep -wE 'CONFIG_ETHERNET|CONFIG_IGC|CONFIG_NET_VENDOR_INTEL' /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 igcPrints 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/cloud-amd64, arm64/cloud-arm64
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_ETHERNET, CONFIG_IGC, CONFIG_NET_VENDOR_INTEL
- 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
- 2026-08-22 (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
- 0.18%, higher than 7.4% 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 |
|---|---|---|
| 6.15 | 6.18.45 | 5fd121971912 |
| 6.15 | 7.1.9 | 0cc7aa6e0d19 |
| 6.15 | 7.2 | 849b1664dbda |
| 6.14.2 | 0 | 0 |
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 flaw is reached only through local AF_XDP setup (socket, UMEM registration, TX ring submission) and zero-copy driver transmit on bound netdev queues; remote peers cannot directly trigger xsk_tx_metadata_request() without local control of an AF_XDP socket.
- AC:LAttack complexity, low
- The attacker fully controls mmap'd UMEM metadata and can race concurrent writes (or helper threads) between early validation in get_ctx/get_metadata and the later xsk_tx_metadata_request() read, reliably creating the TOCTOU window.
- PR:LPrivileges required, low
- Creating an AF_XDP socket requires CAP_NET_RAW in the relevant network user namespace (xsk_create); unprivileged local users can obtain this capability via user/network namespaces (e.g., unshare -Urn), matching CNA guidance for net stack local attack surface.
- UI:NUser interaction, none
- Exploitation requires only the attacker configuring AF_XDP zero-copy TX, crafting metadata, and submitting descriptors; no separate victim user action is needed beyond normal attacker-controlled local execution.
- S:UScope, unchanged
- Impact is confined to kernel/driver transmit state on the host where the AF_XDP socket runs; it does not cross VM, IOMMU, or sandbox security boundaries into another authority.
- C:HConfidentiality impact, high
- Bypassing metadata validation can enable unchecked launch-time/checksum offload handlers that misread fields and corrupt kernel TX ring/descriptor state, providing a plausible kernel memory disclosure primitive consistent with related AF_XDP metadata TOCTOU issues.
- I:HIntegrity impact, high
- After validation, userspace can flip flags and request fields so zero-copy drivers (igc/stmmac/mlx5/libeth) program hardware with unvalidated launch_time or checksum requests, corrupting in-kernel TX descriptors and transmit control structures.
- A:HAvailability impact, high
- Illegal hardware offload activation or corrupted TX ring accounting can kernel-oops, panic, or wedge NIC transmit queues; the attacker can repeatedly trigger the path via continuous AF_XDP zero-copy transmissions.