Integer underflow in tpm2-tss - CVE-2026-109545
Published: November 6, 2026
Vulnerability identifier: #VU159842
CSH Severity: Medium
CVSS v4: 5.2 [CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-109545
CWE-ID: CWE-191
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated attacker with physical access to the TPM bus to corrupt heap memory in applications using tpm2-tss.
The vulnerability exists due to unchecked subtraction in the SPI and I2C TCTI response handlers when a TPM response declares a size of six bytes or less. An unauthenticated attacker with physical access to the TPM bus can supply crafted responses that trigger oversized transfers of attacker-controlled data into the heap response buffer.
Affected software
tpm2-tss
Fedora
tpm2-tss
Fedora
tpm2-tss
How to mitigate CVE-2026-109545
Install security update from vendor's website.
tpm2-tss - addressed in versions 4.1.5, 4.2.1
tpm2-tss - addressed in versions 4.1.5-1.fc43, 4.1.5-1.fc44, 4.2.1-1.fc45
tpm2-tss - addressed in versions 4.1.5-1.fc43, 4.1.5-1.fc44, 4.2.1-1.fc45