OP-TEE optee_os up to 4.10 on ARM rsassa.c emsa_pkcs1_v1_5_encode integer overflow

Summaryinfo

A vulnerability was found in OP-TEE optee_os up to 4.10 on ARM. It has been rated as problematic. This affects the function emsa_pkcs1_v1_5_encode of the file core/drivers/crypto/crypto_api/acipher/rsassa.c. Performing a manipulation results in integer overflow. This vulnerability is cataloged as CVE-2026-33662. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in OP-TEE optee_os up to 4.10 on ARM. This affects the function emsa_pkcs1_v1_5_encode of the file core/drivers/crypto/crypto_api/acipher/rsassa.c. The manipulation with an unknown input leads to a integer overflow vulnerability. CWE is classifying the issue as CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-33662 since 03/23/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/28/2026).

The vulnerability scanner Nessus provides a plugin with the ID 310511 (Linux Distros Unpatched Vulnerability : CVE-2026-33662), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (310511). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• OP-TEE

Name

• optee_os

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10

Website

• Product: https://github.com/OP-TEE/optee_os/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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