Linux Kernel TPM Null Key Name Mismatch Enables TPM Reset Attacks
CVE-2026-98845 Published on October 18, 2026
tpm: Disable TPM on null key name mismatch
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.
Products Associated with CVE-2026-98845
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Affected Versions
Linux:- Version cc7d8594342a25693d40fe96f97e5c6c29ee609c and below a03d0c64cd827a622578623a78defd66b6593b82 is affected.
- Version cc7d8594342a25693d40fe96f97e5c6c29ee609c and below 96c46c75b0d470b4204f9fe1bdb075cd2ebaebfa is affected.
- Version cc7d8594342a25693d40fe96f97e5c6c29ee609c and below f6599d8830fe7ddab7334cc17846fd9ac9a7fa50 is affected.
- Version cc7d8594342a25693d40fe96f97e5c6c29ee609c and below 015fb29a748342a186f37b602ac70017098c8251 is affected.
- Version 294984ce51c19c2af3d0d71e1c8bd589bc86b8e2 is affected.
- Version 386c7cc6c06d64cbf36d15c5e2319814765e107c is affected.
- Version 6.11.7 and below 6.12 is affected.
- Version 6.11.10 and below 6.12 is affected.
- Version 6.12 is affected.
- Before 6.12 is unaffected.
- Version 6.12.113, <= 6.12.* is unaffected.
- Version 6.18.56, <= 6.18.* is unaffected.
- Version 7.2.10, <= 7.2.* is unaffected.
- Version 7.3-rc6, <= * is unaffected.