CVE-2026-98761

Received Received - Intake

USB Type-C Port Reset Failure in Linux Kernel

Publication date: 2026-10-18

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: usb: typec: tcpm: recover after failure to start the frs ams Reset the port if the tcpm fails to start the FAST_ROLE_SWAP AMS by initiating error recovery on it. This helps in cases where some cables (incorrectly) signal an FRS to an FRS capable port during disconnection. The TCPC autonomously starts sourcing VBUS on detecting the FRS signal. However, the VBUS sourcing is left on when the FAST_ROLE_SWAP AMS fails to start (as tcpm_sink_tx_ok is 0 as CC is open due to the cable disconnect). This is because the code sets the state to INVALID_STATE without resetting the port state. Log snippet before changes: [ 101.401960] AMS FAST_ROLE_SWAP start [ 101.401971] Sink TX No Go [ 101.401982] sourcing vbus [ 101.401987] VBUS on [ 101.402159] VBUS on [ 109.257809] CC1: 0 -> 0, CC2: 5 -> 0 [state SNK_READY, polarity 1, disconnected] [ 111.267442] VBUS on After changes: [ 70.541211] AMS FAST_ROLE_SWAP start [ 70.541220] Sink TX No Go [ 70.541228] state change SNK_READY -> ERROR_RECOVERY [rev3 NONE_AMS] [ 70.541362] VBUS on [ 70.541365] sourcing vbus [ 70.541367] VBUS on [ 70.541374] state change ERROR_RECOVERY -> PORT_RESET [rev3 NONE_AMS] [ 70.541410] disable vbus discharge ret:0 [ 70.543028] Setting usb_comm capable false [ 70.544009] Setting voltage/current limit 0 mV 0 mA [ 70.544034] polarity 0 [ 70.544239] Requesting mux state 0, usb-role 0, orientation 0 [ 70.555550] cc:=0 [ 70.555595] pending state change PORT_RESET -> PORT_RESET_WAIT_OFF @ 100 ms [rev3 NONE_AMS] [ 70.555697] VBUS off [ 70.555702] VBUS VSAFE0V [ 70.555762] CC1: 5 -> 0, CC2: 0 -> 0 [state PORT_RESET, polarity 0, disconnected] [ 70.587794] VBUS off [ 70.587799] VBUS VSAFE0V [ 70.655672] state change PORT_RESET -> PORT_RESET_WAIT_OFF [delayed 100 ms] [ 70.655682] state change PORT_RESET_WAIT_OFF -> SNK_UNATTACHED [rev3 NONE_AMS] [ 70.655686] Start toggling [ 70.656274] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]

CVSS Scores

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Meta Information

Published

2026-10-18

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-18

EPSS Evaluated

N/A

NVD

CVE-2026-98761

EUVD

EUVD-2026-103846

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	0908c5aca31eb5e0c72d7a5dba422629b88e877d
Linux	Linux	0908c5aca31eb5e0c72d7a5dba422629b88e877d
Linux	Linux	0908c5aca31eb5e0c72d7a5dba422629b88e877d
Linux	Linux	0908c5aca31eb5e0c72d7a5dba422629b88e877d
Linux	Linux	5.12

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a failure in the USB Type-C Port Manager (TCPM) to properly handle Fast Role Swap (FRS) operations during cable disconnections. When an incorrect cable signals an FRS to a capable port, the port may incorrectly source VBUS power even after the FRS fails to start. The fix ensures the port resets to a safe state after such failures.

Detection Guidance

This vulnerability is specific to the Linux kernel's USB Type-C port manager (tcpm) and relates to failure in Fast Role Swap (FRS) handling. Detection requires checking kernel logs for FRS-related errors or unexpected VBUS sourcing during disconnection. Monitor logs for 'FAST_ROLE_SWAP start' followed by 'Sink TX No Go' and 'VBUS on' without proper recovery. Use commands like 'dmesg | grep -i frs' or 'journalctl -k | grep -i frs' to search for related events.

Impact Analysis

This vulnerability could lead to unexpected power delivery issues during USB Type-C disconnections, potentially causing device malfunctions or damage. It may also disrupt data transfer stability in connected devices.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a low-level USB Type-C power delivery issue in the Linux kernel that could cause improper power state handling during disconnection events. No evidence suggests it impacts data protection, privacy, or security controls required by these regulations.

Mitigation Strategies

Update the Linux kernel to a version that includes the fix for this issue. The vulnerability is resolved by ensuring proper error recovery when FRS fails to start. Check your distribution's security updates or kernel patches. If immediate update is not possible, disable Fast Role Swap functionality in the kernel configuration or via module parameters as a temporary workaround.

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