🛡️ CVE-2026-40257 on Ubuntu — optee-os

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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`.

Distribution advisory

This page covers CVE-2026-40257 as tracked by Ubuntu, for the package optee-os. No fixed version has been recorded for this distribution yet.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software and timeline

Affected software: optee-os. Published on 6 July 2026 and last revised on 9 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
github.com (Report)

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-07-06
Updated 2026-08-11
Modified 2026-07-09
Fix URL N/A

Affected Packages

Software From version Fixed in
optee-os — —

Vulnerability Monitoring

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More UBUNTU CVE 2026 advisories

Part of UBUNTU CVE 2026 in the advisory index.