OP-TEE OS through version 4.10.0 contains a buffer underwrite vulnerability in the RSA NOPAD encrypt and decrypt operations implemented in the mbedTLS software backend and SE050 hardware driver. When a malicious Trusted Application provides an input length (src_len) greater than the RSA modulus size (rsa_len), the subtraction expression used to calculate buffer offsets wraps around to a large unsigned value. This leads to a memcpy operation that writes data before the intended destination buffer in the S-EL1 secure-world heap memory, causing memory corruption. This vulnerability was fixed in commit 7b8b494.

The vulnerability allows a malicious Trusted Application with high privileges to corrupt secure-world heap memory by writing attacker-controlled data out-of-bounds before the destination buffer. This memory corruption could undermine the integrity and security of the trusted execution environment, potentially leading to privilege escalation or other security breaches within the secure world. However, exploitation requires high privileges (Trusted Application level) and local access.

A fix for this vulnerability is available in OP-TEE OS after commit 7b8b494. Users should upgrade to a version of OP-TEE OS that includes this fix. Since no official patch or vendor advisory content is provided here, confirm the patch status and upgrade instructions from the OP-TEE project repository or official advisories. Until patched, restrict the execution of untrusted Trusted Applications to mitigate risk.