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 emsa_pkcs1_v1_5_encode() in core/drivers/crypto/crypto_api/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-v1_5 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.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://github.com/OP-TEE/optee_os/security/advisories/GHSA-4cf8-v5g3-73gr Patch, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 7.5 · trustedfirmwareNVD modified 2026-10-26 22:10
Affected (CPE criteria) 1
cpe:2.3:o:trustedfirmware:op-tee:*:*:*:*:*:*:*:*
References 1
- https://github.com/OP-TEE/optee_os/security/advisories/GHSA-4cf8-v5g3-73gr Patch, Vendor Advisory