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CVE-2026-74285
net: Stop leased rxq before uninstalling its memory provider
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/core. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74285 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
netif_rxq_cleanup_unlease() tears down the memory provider that was installed on a physical RX queue through a netkit queue lease. It currently revokes the provider's DMA mappings before stopping the physical queue: __netif_mp_uninstall_rxq(virt_rxq, p); /* DMA unmap */ __netif_mp_close_rxq(phys_rxq->dev, rxq_idx, p); /* queue stop */ This inverts the ordering used by the regular teardown paths (normal device unregister and the io_uring zcrx close path), which stop the queue before revoking the provider's mappings. With the physical queue still live, its NAPI can keep consuming net_iov entries from the page_pool alloc cache after the __netif_mp_uninstall_rxq() has already cleared their dma_addr, opening a window for the device to DMA to a stale or zero address. Fix it by swapping the two calls so the queue is stopped (and its NAPI quiesced) before the provider is uninstalled. No functional regression was observed across repeated runs of the nk_qlease.py HW selftest, which exercises the lease teardown path; this was tested against fbnic QEMU emulation.
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.
net/core/netdev_rx_queue.c
- What this is
- NETWORKING [GENERAL]MAINTAINERS section matched on net/ · netdev@vger.kernel.org · Maintained
Show whether Debian builds this, per release
Debian builds this code. Every release with an answer below compiles the affected file into the kernels it ships. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sidy
- ?
- not established - no Makefile entry for the affected file
- y
- built into the kernel image on every flavour - only a patch removes it
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.
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 Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- net/core
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 | 03f4c6ed3cff |
| 7.1 | 7.2 | 37314c9dbe95 |
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
- Exploitation requires local netlink/rtnl actions (netdev-genl QUEUE_CREATE, netkit teardown via ip link del) that invoke netif_rxq_cleanup_unlease(); remote packets alone cannot reach this teardown path.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by keeping RX traffic/NAPI active on the leased physical queue while concurrently deleting netkit or tearing down the lease with a memory provider installed.
- PR:LPrivileges required, low
- Queue leasing, netkit creation, and memory-provider binding all require CAP_NET_ADMIN, which unprivileged users can obtain inside user/network namespaces via unshare without init-namespace root.
- UI:NUser interaction, none
- No victim interaction is required; the attacker configures the netkit lease, installs an io_uring zcrx or devmem memory provider, generates RX load, and triggers lease teardown themselves.
- S:CScope, changed
- Stale or zero DMA addresses let the physical NIC write outside intended buffers, crossing container/host and DMA mapping boundaries when a user-namespace tenant leases a host physical RX queue.
- C:HConfidentiality impact, high
- Premature DMA unmap while NAPI still hands net_iov buffers to hardware enables misplaced RX DMA that can disclose or corrupt adjacent kernel/host memory beyond the intended mapping.
- I:HIntegrity impact, high
- The device may DMA received packet data to a cleared or stale dma_addr, providing an attacker-influenced arbitrary kernel memory write primitive during queue-lease teardown.
- A:HAvailability impact, high
- Invalid DMA to stale or zero addresses can cause kernel oops/panic, NIC hangs, or fatal memory corruption during lease teardown even when full exploitation is not attempted.