CVE-2026-33662: OP-TEE: RSASSA EMSA- PKCS1-v1_5 underflow in emsa_pkcs1_v1_5_encode()
OP-TEE is a Trusted Execution Environment (TEE) designed as companion to a non-secure Linux kernel running on Arm; Cortex-A cores using the TrustZone technology. From 3.8.0 to 4.10, in the function emsapkcs1v15encode() in core/drivers/crypto/cryptoapi/acipher/rsassa.c, the amount of padding needed, "PS size", is calculated by subtracting the size of the digest and other fields required for the EMA-PKCS1-v15 encoding from the size of the modulus of the key. By selecting a small enough modulus, this subtraction can overflow. The padding is added as a string of 0xFF bytes with a call to memset(), and an underflowed integer will cause the memset() call to overwrite until OP-TEE crashes. This only affects platforms registering RSA acceleration.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33662?
CVE-2026-33662 has been classified with a medium severity level due to potential impacts on cryptographic operations.
How do I fix CVE-2026-33662?
To fix CVE-2026-33662, you should upgrade your OP-TEE version to 4.10 or later.
What software is affected by CVE-2026-33662?
CVE-2026-33662 affects OP-TEE versions from 3.8.0 up to 4.10.
What is the underlying issue in CVE-2026-33662?
The issue in CVE-2026-33662 is an underflow in the emsa_pkcs1_v1_5_encode() function which can lead to security vulnerabilities.
How can CVE-2026-33662 impact my organization?
If exploited, CVE-2026-33662 could compromise cryptographic functions, potentially leading to unauthorized data access.