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CVE-2026-40257 OP-TEE CVE debrief

A heap overflow vulnerability exists in OP-TEE, a Trusted Execution Environment (TEE) designed for Arm-based systems, specifically affecting versions from 3.21.0 up to but not including 4.11.0. This issue arises from an off-by-one error in the ARM Crypto Extensions accelerated SHA-3 implementation. The vulnerability can lead to a massive heap overflow that corrupts all TEE kernel memory following the hash state. This affects platforms built with `CFG_CRYPTO_WITH_CE82=y`, which enables ARMv8.2+ with SHA3 Crypto Extensions. The issue has been patched in version 4.11.0. As a temporary workaround, users can disable SHA3 Crypto Extensions by setting `CFG_CRYPTO_WITH_CE82=n`.

Vendor
OP-TEE
Product
optee_os
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-06
Original CVE updated
2026-07-07
Advisory published
2026-07-06
Advisory updated
2026-07-07

Who should care

Organizations utilizing OP-TEE on Arm-based systems, especially those with `CFG_CRYPTO_WITH_CE82=y` enabled, should prioritize patching to version 4.11.0 or applying the recommended workaround. This includes industries relying on secure execution environments, such as finance, healthcare, and telecommunications.

Technical summary

The vulnerability is caused by an off-by-one error in the ARM Crypto Extensions accelerated SHA-3 implementation within OP-TEE. This error occurs in the `optee_os` codebase, specifically in the cryptographic processing logic. The issue allows for a heap overflow, potentially leading to arbitrary code execution or denial of service within the TEE. The vulnerability is exacerbated by its impact on TEE kernel memory, which could compromise the integrity of the secure environment.

Defensive priority

High

Recommended defensive actions

  • Apply the official patch by updating to OP-TEE version 4.11.0 or later.
  • As a temporary measure, disable SHA3 Crypto Extensions by setting `CFG_CRYPTO_WITH_CE82=n` during compilation.
  • Conduct a thorough inventory of systems and applications using OP-TEE to identify all potentially affected components.
  • Implement compensating controls, such as monitoring for suspicious activity within the TEE environment.
  • Verify the integrity of TEE kernel memory and perform regular security audits.

Evidence notes

The CVE record was published on 2026-07-06T17:16:31.253Z and was last modified on 2026-07-07T18:56:50.250Z. The NVD entry is currently Analyzed. The vulnerability details were obtained from the official CVE record and the NVD database, which provide comprehensive information about the affected versions and potential impact.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40257 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40257

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-40257 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40257

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.