Integer overflow in Linaro Op-Tee
CVE-2026-33662
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.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (46.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.002
Affected products
- Linaro Op-Tee
- Op-Tee Optee OS — versions >= 3.8.0, <= 4.10
- Trustedfirmware Op-Tee
Weakness classification (CWE)
References
- github.com/OP-TEE/optee_os/security/advisories/GHSA-4cf8-v5g3-73gr (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-33662?
- CVE-2026-33662 is a high-severity vulnerability in Linaro Op-Tee, classified under Integer Overflow or Wraparound. CVSS score: 7.5/10. Published 2026-04-24.
- How severe is CVE-2026-33662?
- High severity. CVSS v3 base score is 7.5 out of 10.