CVE-2026-40257: OP-TEE has SHA-3 accelerated finalize heap overflow
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 Extensions accelerated SHA-3 implementation has an off-by-one error that can cause a massive heap overflow that corrupts all TEE kernel memory following the hash state. This affects all platforms built with CFGCRYPTOWITHCE82=y (ARMv8.2+ with SHA3 Crypto Extensions). Version 4.11.0 contains a patch. As a workaround, disable SHA3 Crypto Extensions with CFGCRYPTOWITHCE82=n.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.11.0 - Configuration
As a workaround, disable SHA3 Crypto Extensions by setting `CFG_CRYPTO_WITH_CE82=n` (affected when built with `CFG_CRYPTO_WITH_CE82=y`, ARMv8.2+ with SHA3 Crypto Extensions).
OP-TEE ARM Crypto Extensions (CFG_CRYPTO_WITH_CE82) CFG_CRYPTO_WITH_CE82 = n
Event History
Frequently Asked Questions
What is the severity of CVE-2026-40257?
CVE-2026-40257 has a medium severity rating of 5.5.
How do I fix CVE-2026-40257?
To fix CVE-2026-40257, update OP-TEE to version 4.11.0 or later.
What causes the CVE-2026-40257 vulnerability?
CVE-2026-40257 is caused by an off-by-one error in the ARM Crypto Extensions accelerated SHA-3 implementation.
Which versions of OP-TEE are affected by CVE-2026-40257?
Versions of OP-TEE from 3.21.0 up to, but not including, 4.11.0 are affected by CVE-2026-40257.
What are the consequences of CVE-2026-40257?
The consequences of CVE-2026-40257 include a potential heap overflow that could lead to remote code execution.