CVE-2026-98750: tty: fix saved termios reset race
In the Linux kernel, the following vulnerability has been resolved:
tty: fix saved termios reset race
Resetting saved termios state on device registration is needed where a minor number can be reused for an entirely different device and where the old settings may prevent the port from even being opened (e.g. when CLOCAL is not set).
Not all TTY drivers guarantee that the minor number is no longer in use when registering devices however, something which can lead to a use-after-free when closing a TTY (and saving its termios) races with re-registration.
Add a new TTYDRIVERRESETSAVEDTERMIOS flag to request that any saved termios state is reset on registration and only set it for drivers that make sure that the minor number is no longer in use.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.113-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 7.2.10-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 5.10.273 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 5.15.224 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.1.191 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.6.160 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.12.113 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.18.56 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.2.10 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Configuration
Add the TTY_DRIVER_RESET_SAVED_TERMIOS flag to request resetting saved termios state on device registration, and set it only for TTY drivers that ensure the minor number is no longer in use.
Linux kernel TTY drivers TTY_DRIVER_RESET_SAVED_TERMIOS = set only for drivers that guarantee the minor number is no longer in use
Event History
Frequently Asked Questions
Which systems are exposed to this race?
Systems using affected Linux kernel TTY drivers are exposed when a TTY device is re-registered while another close operation can still save termios state for the same minor number. The issue is specifically relevant to drivers that do not guarantee that a minor number is no longer in use when registering a device.
What conditions are required to trigger the use-after-free?
A TTY close operation that saves termios state must race with device re-registration. Reuse of a minor number, potentially for a different device, is part of the scenario addressed by the fix.
What does the fix change?
The fix adds a TTY_DRIVER_RESET_SAVED_TERMIOS flag for resetting saved termios state during registration. The flag is intended only for drivers that ensure the relevant minor number is no longer in use.