CVE-2026-98761 Linux CVE debrief

Who should care

Linux kernel maintainers, developers, and users of Linux-based systems, especially those utilizing USB Type-C Power Management (TCPM) functionality, should review and apply patches. Affected operators and security teams need to verify system kernel versions and apply patches to prevent potential VBUS sourcing issues. Vulnerability management and platform security teams should prioritize patching and monitor for related security advisories.

Why it matters

A vulnerability in the Linux kernel's USB Type-C Power Management (TCPM) can lead to potential VBUS sourcing issues upon FAST_ROLE_SWAP AMS failure. Defenders should review and apply patches, monitor kernel updates, and verify system kernel versions.

• Defenders should verify Linux kernel versions and apply patches to prevent potential VBUS sourcing issues.
• Affected systems may require updated kernel versions to ensure proper TCPC functionality.

Technical summary

The Linux kernel's USB Type-C Power Management (TCPM) has a vulnerability that can lead to VBUS sourcing issues when the FAST_ROLE_SWAP AMS fails to start. This can occur with certain cables that incorrectly signal an FRS to an FRS-capable port during disconnection. The fix involves resetting the port in such failure cases to prevent VBUS from being left on. Affected systems may require updated kernel versions to ensure proper TCPC functionality. Defenders should review and apply patches, monitor kernel updates, and verify system kernel versions.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the provided kernel patches to ensure the fix is implemented.
• Monitor Linux kernel updates for any related security advisories.
• Verify that affected systems have the updated kernel version deployed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The issue arises from the TCPC's autonomous start of sourcing VBUS upon detecting the FRS signal, but failing to reset the port state when the FAST_ROLE_SWAP AMS fails to start. This results in VBUS being left on. The fix introduces a port reset in such failure cases.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.