CVE-2025-68792 Overview
A memory corruption vulnerability has been identified in the Linux kernel's TPM2 (Trusted Platform Module 2.0) sessions subsystem. The vulnerability exists in the name_size function, which lacks proper range validation when indexing with TPM_ALG_ID values. This missing bounds check allows out-of-range indexing that could lead to memory corruption.
Critical Impact
Exploitation of this vulnerability could result in memory corruption within the kernel's TPM subsystem, potentially affecting system integrity and security-critical TPM operations.
Affected Products
- Linux kernel with TPM2 sessions support enabled
- Systems utilizing TPM2 hardware security modules
- Kernel configurations with CONFIG_TPM enabled
Discovery Timeline
- 2026-01-13 - CVE CVE-2025-68792 published to NVD
- 2026-01-13 - Last updated in NVD database
Technical Details for CVE-2025-68792
Vulnerability Analysis
The vulnerability resides in the TPM2 sessions implementation within the Linux kernel. The name_size function accepts a TPM_ALG_ID parameter and uses it directly as an index without performing any bounds validation. When an attacker or malformed data provides an unrecognized or out-of-range algorithm identifier, the function proceeds to use this value for array indexing, leading to out-of-bounds memory access.
The fix addresses this issue by implementing strict validation for known TPM_ALG_ID values and returning -EINVAL for any unrecognized values. Additionally, the patch makes the tpm_buf_append_name and tpm_buf_fill_hmac_session functions fallible, allowing errors to be detected and handled before generating any erroneous TPM traffic. The authorization session is also properly terminated on failure to prevent session state corruption.
Root Cause
The root cause is missing input validation in the name_size function. The function directly uses the TPM_ALG_ID value as an array index without verifying that the value falls within the expected range of known algorithm identifiers. This is a classic case of improper input validation leading to out-of-bounds array access.
Attack Vector
An attacker could potentially exploit this vulnerability by providing crafted TPM algorithm identifiers through the TPM subsystem interface. The attack vector details are:
- Local Access Required: Exploitation typically requires local access to the system with permissions to interact with TPM devices
- Privilege Requirements: Access to TPM device interfaces is typically restricted, limiting the attack surface
- Impact: Successful exploitation could corrupt kernel memory, potentially leading to denial of service, privilege escalation, or system instability
The vulnerability mechanism involves malformed TPM_ALG_ID values bypassing validation and being used directly as array indices. This can cause reads or writes to unintended memory locations within the kernel address space. The kernel commit provides detailed technical information about the fix implementation.
Detection Methods for CVE-2025-68792
Indicators of Compromise
- Unexpected kernel crashes or panics related to TPM subsystem operations
- Anomalous TPM-related error messages in system logs (dmesg output)
- Memory corruption indicators in kernel debugging output
- TPM authorization session failures or unexpected terminations
Detection Strategies
- Monitor kernel logs for TPM subsystem errors using dmesg | grep -i tpm
- Deploy kernel memory corruption detection tools such as KASAN (Kernel Address Sanitizer)
- Review TPM device access patterns for anomalous algorithm identifier usage
- Implement SentinelOne Singularity XDR for real-time kernel-level threat detection
Monitoring Recommendations
- Enable kernel auditing for TPM device access (/dev/tpm*)
- Configure alerts for TPM-related kernel error messages
- Monitor for unusual process interactions with TPM devices
- Track kernel module loading events for TPM drivers
How to Mitigate CVE-2025-68792
Immediate Actions Required
- Apply the latest kernel security patches containing the fix for CVE-2025-68792
- Review and restrict access permissions to TPM device files (/dev/tpm*)
- Monitor systems for signs of exploitation until patches are deployed
- Consider temporarily disabling TPM functionality if not critical to operations
Patch Information
The vulnerability has been addressed in the Linux kernel stable tree. The fix implements proper range checking for TPM_ALG_ID values and adds error handling to prevent memory corruption.
Patch Commits:
Organizations should update to the latest kernel version from their distribution that includes these fixes.
Workarounds
- Restrict TPM device access to only essential system services and trusted users
- Implement mandatory access controls (SELinux/AppArmor) to limit TPM device interactions
- Monitor and audit all TPM-related system calls using kernel auditing
- Deploy endpoint detection solutions like SentinelOne to detect exploitation attempts
# Restrict TPM device permissions as a temporary mitigation
chmod 600 /dev/tpm*
chown root:root /dev/tpm*
# Verify current TPM device permissions
ls -la /dev/tpm*
# Check kernel version to verify patch status
uname -r
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
