CVE-2026-98761 usb: typec: tcpm: recover after failure to start the frs ams
A physical USB cable disconnection during a fast role swap can leave VBUS powered, causing a denial of service in the Linux kernel USB Type-C subsystem.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-98761?
CVE-2026-98761 is a denial of service vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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]
Which versions are affected by CVE-2026-98761?
How do I fix CVE-2026-98761?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-98761 being exploited?
There is no known exploitation of CVE-2026-98761 in the wild and no public exploit code.
Sources
Also known as AZL-108984, BELL-CVE-2026-98761, DEBIAN-CVE-2026-98761, GHSA-fcv9-h4wq-59j8, UBUNTU-CVE-2026-98761.