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CVE-2026-74495
igbvf: Fix leak in TX DMA error cleanup
Published 2026-08-15 (2 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-2026-74495 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
If an error is encountered while mapping TX buffers, the driver should unmap any buffers already mapped for that skb. Because count is incremented before each frag mapping, it will always match the correct number of unmappings needed when dma_error is reached. Decrementing count before the while loop in dma_error causes an off-by-one error. If any mapping was successful before an unsuccessful mapping, exactly one DMA mapping (the head) would leak. This bug was introduced by a 2010 fix for an endless loop in dma_error. All other affected drivers have already been fixed.
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/igbvf/netdev.c
- What this is
- INTEL ETHERNET DRIVERSMAINTAINERS section matched on drivers/net/ethernet/intel/*/ · intel-wired-lan@lists.osuosl.org · Maintained
- Kernel module
- igbvf
Check it on the machine
grep -wE 'CONFIG_ETHERNET|CONFIG_IGBVF|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 igbvfPrints 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, sid, bookworm · linux-6.12Mnot 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_IGBVF, 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
- 2026-08-15 (2 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
- 0.51%, higher than 42.5% 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 |
|---|---|---|
| 2.6.33 | 5.10.265 | e42b7225c45f |
| 2.6.33 | 5.15.216 | e3ed89c257f6 |
| 2.6.33 | 6.1.183 | 56726ff12cb6 |
| 2.6.33 | 6.6.151 | 31089f4eab42 |
| 2.6.33 | 6.12.103 | bc25d56c03e4 |
| 2.6.33 | 6.18.44 | 845a9cdd9b03 |
| 2.6.33 | 7.1.8 | df07003b5a6c |
| 2.6.33 | 7.2 | 0565052b7e2f |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 bug is in the igbvf VF transmit path reached whenever egress skbs are queued, including fragmented replies or forwarded traffic from remote peers on SR-IOV cloud/tenant networks with internet-facing VFs.
- AC:LAttack complexity, low
- No race is required; an attacker can repeatedly drive fragmented TX skbs and SWIOTLB/DMA-mapping pressure until skb_frag_dma_map fails after a successful head map, deterministically hitting the off-by-one dma_error cleanup.
- PR:NPrivileges required, none
- Reaching ndo_start_xmit via normal sockets on the VF requires no kernel capabilities; co-tenant or internet-facing traffic can induce the leaky dma_error path without local credentials on the victim.
- UI:NUser interaction, none
- No victim interaction is needed beyond the VF carrying traffic; the leak occurs automatically in dma_error cleanup during transmit once mapping failure conditions are met.
- S:UScope, unchanged
- Impact is confined to the kernel/DMA resources of the guest or host running igbvf and does not by itself cross a hypervisor, IOMMU isolation, or separate security authority boundary.
- C:HConfidentiality impact, high
- The error path frees the skb while its head DMA/IOMMU mapping remains in buffer_info, so freed pages can be reallocated while still mapped, enabling plausible kernel memory disclosure via stale DMA state.
- I:HIntegrity impact, high
- Reusing the descriptor slot without unmapping the leaked head mapping corrupts driver/IOMMU metadata and accumulates orphan mappings, a defensible path to driver heap corruption or write primitives.
- A:HAvailability impact, high
- Each leaked TX DMA/IOMMU mapping consumes finite SWIOTLB/IOMMU resources; repeated triggering can exhaust mappings and break transmit or disable the VF entirely.