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CVE-2026-63857
net: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()
Published 2026-07-19 (3 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-2026-63857 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 | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The transmit loop in airoha_dev_xmit() reads fragment address and length during its final iteration, when the loop index equals skb_shinfo(skb)->nr_frags, at which point the fragment data is uninitialized. While these values are never consumed, the read itself is unsafe and may trigger a page fault. Fix this by avoiding the fragment read on the last iteration. Additionally, move the skb pointer from the first to the last used packet descriptor, so that airoha_qdma_tx_napi_poll() defers freeing the skb until the final descriptor is processed.
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/airoha/airoha_eth.c
- What this is
- AIROHA ETHERNET DRIVERMAINTAINERS section matched on drivers/net/ethernet/airoha/ · linux-arm-kernel@lists.infradead.org · Maintained
Check it on the machine
grep -wE 'CONFIG_ETHERNET|CONFIG_NET_AIROHA|CONFIG_NET_VENDOR_AIROHA' /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 3 releases. The build rule could not be established for 1 release, 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_ETHERNET, CONFIG_NET_AIROHA, CONFIG_NET_VENDOR_AIROHA
- 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
- 0.65%, higher than 50.1% 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 |
|---|---|---|
| 6.11 | 6.18.33 | f670fa4b19ce |
| 6.11 | 7.0.10 | d78c8ab7bd84 |
| 6.11 | 7.1 | bde34e84edc8 |
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 netdev TX (`ndo_start_xmit`) on Airoha EN7581 WAN/LAN interfaces; a remote attacker can trigger transmission by sending packets that cause responses, NAT forwarding, or bridged/routed egress without local access.
- AC:LAttack complexity, low
- Any outbound skb traversing this driver hits the defective loop deterministically; an attacker can reliably provoke multi-fragment transmits (scatter/gather is enabled) to also trigger the premature-skb-free UAF without depending on uncontrollable timing or layout.
- PR:NPrivileges required, none
- Exploitation requires only the ability to send network traffic to or through the device's registered netdevs; no local account, capability, or authentication is needed on internet-facing router/CPE deployments.
- UI:NUser interaction, none
- No victim interaction is required beyond normal always-on network traffic handled by the kernel stack.
- S:UScope, unchanged
- Impact is confined to kernel memory and the host running the Airoha driver; it does not cross a VM/hypervisor or IOMMU security boundary.
- C:HConfidentiality impact, high
- The final loop iteration performs an out-of-bounds read of uninitialized `skb_frag_t` contents that may contain stale kernel heap data, and the companion skb lifetime bug creates a use-after-free that can be leveraged for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Premature freeing of the skb while later TX descriptors still DMA mapped fragment memory is a heap use-after-free that can be exploited for arbitrary kernel writes or code execution, not merely a discarded read.
- A:HAvailability impact, high
- Reading garbage fragment metadata can cause a kernel page fault/oops, and the skb use-after-free can crash or panic the system during subsequent DMA completion or skb reuse.