Medium severity · published Jul 6, 2026
CVE-2026-40257
OP-TEE has SHA-3 accelerated finalize heap overflow
5.5
CVSS
0.2%
EPSS
No
On KEV
Description
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 `CFG_CRYPTO_WITH_CE82=y` (ARMv8.2+ with SHA3 Crypto Extensions). Version 4.11.0 contains a patch. As a workaround, disable SHA3 Crypto Extensions with `CFG_CRYPTO_WITH_CE82=n`.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 4% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OP
optee_os · OP-TEE
>= 3.21.0, < 4.11.0 · source: vendor
OP
Op-tee · Trustedfirmware
3.21.0 through 4.10.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40257
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-40257
Mitigation
https://github.com/OP-TEE/optee_os/security/advisories/GHSA-75x4-j8p9-55qv
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