CVE-2026-80616 Overview
CVE-2026-80616 affects the Linux kernel's IEEE 802.15.4 (ieee802154) subsystem. The issue occurs inside cfg802154_switch_netns(), where the kernel invokes WARN_ON() when dev_change_net_namespace() or device_rename() returns -ENOMEM. Deliberate fault injection into memory allocation paths triggers these warnings, producing noisy kernel log splats without any corresponding stability benefit. The Linux Verification Center identified the defect using Syzkaller fuzzing. Maintainers resolved it by removing the pointless WARN_ON() calls on allocation failure. The change is code hygiene that reduces spurious kernel warnings surfaced during fuzz testing and fault injection.
Critical Impact
The defect produces misleading kernel warning splats under memory allocation failure. It does not expose a direct code execution or privilege escalation path.
Affected Products
- Linux kernel ieee802154 subsystem (upstream)
- Stable kernel branches receiving the backported fix commits
- Distributions shipping kernels prior to the patched commits
Discovery Timeline
- 2026-08-28 - CVE-2026-80616 published to NVD
- 2026-08-28 - Last updated in NVD database
Technical Details for CVE-2026-80616
Vulnerability Analysis
The cfg802154_switch_netns() function in the Linux kernel's IEEE 802.15.4 wireless personal area network stack moves a device between network namespaces. During this operation, it calls dev_change_net_namespace() and device_rename(). Both helpers can fail with -ENOMEM when kernel memory is exhausted or when fault injection deliberately fails an allocation.
The original code wrapped these calls in WARN_ON(). When the allocation failed, the kernel emitted a full warning splat containing a stack trace. Syzkaller fuzzing runs at the Linux Verification Center repeatedly triggered this path through fault injection, generating noise that obscured real defects. The fix removes the unnecessary WARN_ON() since an -ENOMEM return under fault injection is expected behavior, not a kernel bug.
Root Cause
The root cause is defensive coding that treated a recoverable, expected error return as a kernel invariant violation. WARN_ON() is reserved for conditions that indicate a genuine bug. Using it on -ENOMEM conflates memory pressure with logic errors.
Attack Vector
There is no documented remote or local attack vector that leverages this defect for code execution or privilege escalation. A local user with the ability to induce memory pressure or use fault injection frameworks such as failslab can trigger repeated warning splats. This creates log noise and, in kernels configured with panic_on_warn, could contribute to a denial of service.
No verified proof-of-concept code is published. The defect and fix are documented in the upstream commits 0569f67ed6a7, 6fcba77571c5, and f4860dd988b1. See Kernel Git Commit 0569f67 for the primary change.
Detection Methods for CVE-2026-80616
Indicators of Compromise
- Kernel log entries containing WARN_ON stack traces originating from cfg802154_switch_netns on unpatched kernels
- Repeated -ENOMEM returns from dev_change_net_namespace() correlated with 802.15.4 device operations
- Unexpected kernel panics on systems configured with panic_on_warn=1 when 802.15.4 namespace switching runs under memory pressure
Detection Strategies
- Compare the running kernel version against the patched stable commits 0569f67ed6a7, 6fcba77571c5, and f4860dd988b1 to identify unfixed builds
- Parse dmesg and journalctl -k output for warning traces referencing cfg802154_switch_netns or the surrounding ieee802154 code paths
- Audit systems that expose 802.15.4 hardware or virtual interfaces, since the affected code only executes on those kernels
Monitoring Recommendations
- Forward kernel logs to a centralized log platform and alert on repeated WARN_ON splats from networking subsystems
- Track memory pressure metrics alongside 802.15.4 interface activity to correlate -ENOMEM events
- Include the affected commit hashes in vulnerability scanning baselines for Linux hosts
How to Mitigate CVE-2026-80616
Immediate Actions Required
- Inventory Linux hosts that build the ieee802154 module or expose 802.15.4 hardware such as low-power WPAN adapters
- Apply the stable kernel update containing commits 0569f67ed6a7, 6fcba77571c5, and f4860dd988b1 from the upstream Linux kernel tree
- Where patching is delayed, disable loading of the ieee802154 module on systems that do not require it
Patch Information
The fix is upstream in the Linux kernel and backported through the stable tree. Review the three referenced commits: Kernel Git Commit 0569f67, Kernel Git Commit 6fcba77, and Kernel Git Commit f4860dd. Distribution vendors will ship the change through their standard kernel updates.
Workarounds
- Blacklist the ieee802154 and mac802154 kernel modules on hosts with no 802.15.4 requirement
- Set panic_on_warn=0 on affected systems to prevent stray warnings from escalating to a panic while patching is scheduled
- Restrict local access on multi-tenant systems to limit fault-injection abuse that generates log noise
# Prevent loading of the ieee802154 module until patched kernels are deployed
echo 'blacklist ieee802154' | sudo tee /etc/modprobe.d/blacklist-ieee802154.conf
echo 'blacklist mac802154' | sudo tee -a /etc/modprobe.d/blacklist-ieee802154.conf
sudo depmod -a
# Verify the module is not currently loaded
lsmod | grep -E 'ieee802154|mac802154'
# Confirm running kernel version and compare against distribution advisories
uname -r
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
