What is CVE-2026-40257?

CVE-2026-40257 is a medium-severity vulnerability in Op-tee Optee_os, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2026-07-06.

How severe is CVE-2026-40257?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Buffer overflow in Op-tee Optee_os

CVE-2026-40257

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. Starting in version 3.21.0 and prior to version 4.11.0, the ARM Crypto Extens…

Vulnerability class: Buffer Overflow

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Op-tee Optee_os — versions >= 3.21.0, < 4.11.0

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-40257?: CVE-2026-40257 is a medium-severity vulnerability in Op-tee Optee_os, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2026-07-06.
How severe is CVE-2026-40257?: Medium severity. CVSS v3 base score is 5.5 out of 10.