CVE-2026-98845 tpm: Disable TPM on null key name mismatch

Not scored Published 18 Oct 2026 Updated 19 Oct 2026

A Linux kernel TPM driver flaw fails to disable the chip on null key mismatch, allowing attackers to bypass TPM reset attack protections.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-98845?

CVE-2026-98845 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

tpm: Disable TPM on null key name mismatch

The null key name check exists to protect against TPM reset attacks, so a mismatch should stop the device from serving further requests. Currently it does not disable the chip when it finds a mismatch.

The mismatch is logged:

tpm tpm0: null key integrity check failed

but the chip keeps serving commands:

/ # tpm2_getcap -c properties-fixed TPM_PT_FAMILY_INDICATOR: as UINT32: 0x08322e3000 as string: "2.0" ...

tpm2_load_null() where the null key name check is run sets the chip as disabled only if the rc is non zero. When the mismatch is seen, rc is zero at that point and it returns success. The other issue is that the caller expects the null key handle to be populated when the function returns 0 which it does here without writing the handle and proceeds assuming the null key handle is valid.

During the test, I noticed that tpm2_start_auth_session() uses the uninitialized stack value as the key handle since tpm2_load_null() returns 0 despite the integrity failure and proceeds with TPM2_CC_START_AUTH_SESS with this value as salt key handle.

Set rc to -ENODEV on the mismatch. The error path then disables the chip and returns the correct code to the caller.

Tested in QEMU with swtpm and CONFIG_TCG_TPM2_HMAC=y by making TPM2_CC_CONTEXT_LOAD fail with TPM2_RC_INTEGRITY and changing the name of the re-created null key. The chip is now disabled on the mismatch.

Which versions are affected by CVE-2026-98845?

How do I fix CVE-2026-98845?

Apply the vendor's patch.

Is CVE-2026-98845 being exploited?

There is no known exploitation of CVE-2026-98845 in the wild and no public exploit code.

Sources

Also known as BELL-CVE-2026-98845, DEBIAN-CVE-2026-98845, GHSA-g3p5-hgwr-rqx7, UBUNTU-CVE-2026-98845.