CVE-2026-45329: ESP-IDF TEE Memory Disclosure Vulnerability – Patch 5.5.5 and 6.0.1

Technical summary

The vulnerability exists in esp_secure_services.c and esp_secure_services_iram.c, where multiple secure-service wrapper functions perform incomplete validation of caller-supplied pointer arguments before passing them to TEE-resident hardware peripherals. These peripherals execute in RISC-V machine mode (M-mode) with unrestricted address-space access, bypassing normal memory isolation. By supplying pointers that reference TEE-exclusive memory regions, an attacker can induce the peripheral to perform cryptographic or memory operations on TEE data and return results to the REE (Rich Execution Environment). The leakage vector varies by wrapper: some return raw bytes, others allow recovery through repeated invocations, and some provide single-bit-per-call side channels. This is fundamentally an input validation and privilege-separation failure (CWE-20, CWE-125, CWE-200).

Business impact

This vulnerability directly threatens the integrity of the TEE isolation model, a core security boundary in IoT and embedded device architectures. Organizations deploying ESP-based systems (microcontrollers, security modules, or SoCs) with TEE-resident cryptographic keys, authentication credentials, or other sensitive state face potential secret extraction. The risk is particularly acute for devices handling financial transactions, access control, or identity operations. While the attack requires local access, it bypasses the entire cryptographic isolation and can enable account compromise, session hijacking, or unauthorized privilege escalation depending on what sensitive material resides in TEE memory.

Affected systems

Affected products: Espressif ESP-IDF versions 5.5.4 and 6.0. Patches are available in versions 5.5.5 and 6.0.1. The vulnerability impacts any ESP microcontroller or SoC running these framework versions with TEE functionality enabled. This includes ESP32-H2, ESP32-C6, ESP32-P4, and other variants that feature TEE hardware support. Devices in the field running vulnerable firmware versions require firmware updates; development environments using these SDK versions should upgrade immediately before deploying new firmware.

Exploitability

Exploitability is limited by the local-access requirement (CVSS attack vector: Local). However, once an attacker achieves code execution in the REE—via a prior vulnerability, supply-chain compromise, physical access, or application-level exploit—this vulnerability becomes trivial to exploit. No special privileges or user interaction are required to invoke the vulnerable wrapper functions. The attack is reliable and repeatable, and the leakage mechanism (direct byte output, computed values, or oracles) makes data extraction feasible. This is not yet included in the CISA KEV catalog, suggesting limited active exploitation in the wild, but the straightforward nature of the attack should inform prioritization.

Remediation

Apply patches immediately: upgrade ESP-IDF to version 5.5.5 (for the 5.5.x line) or 6.0.1 (for the 6.0 line). These updates restore input pointer validation in the vulnerable wrapper functions. Organizations unable to patch firmware immediately should consider mitigations: restrict deployment of vulnerable firmware to isolated networks without untrusted input sources, apply strict application-level access controls to limit REE code execution, and monitor for signs of TEE memory access via peripheral side channels or unusual cryptographic behavior.

Patch guidance

1. Review your ESP-IDF version in use across all development and production devices. 2. Upgrade ESP-IDF repositories to 5.5.5 or 6.0.1 as appropriate. 3. Recompile and test all firmware using the patched SDK version. 4. Conduct regression testing, particularly of TEE-dependent features (secure boot, key derivation, cryptographic acceleration). 5. Deploy updated firmware to all devices in the field; prioritize those holding sensitive secrets in TEE memory. 6. Document the patch version applied for audit and compliance purposes.

Detection guidance

Detection at firmware runtime is difficult; the vulnerability is silent once a payload executes. Focus on preventive controls: (1) audit device inventory for ESP-IDF 5.5.4 and 6.0 deployments; (2) monitor kernel/system logs for unexpected memory access patterns or peripheral-level anomalies; (3) if feasible, instrument TEE interfaces to log unusual pointer patterns or out-of-bounds references; (4) correlate unexpected cryptographic outputs or timing variations with potential exploitation attempts. Network-level detection is limited because the attack is local and does not inherently produce network traffic.

Why prioritize this

This vulnerability merits HIGH priority because it breaks a fundamental security boundary (TEE isolation), allows secret extraction via multiple channels, and affects microcontrollers widely deployed in critical IoT and embedded scenarios. While exploitation requires local access, the ease of exploitation once achieved and the sensitive nature of TEE-resident data (keys, credentials, attestation secrets) amplify the risk. Organizations deploying ESP devices with TEE-dependent security functionality should patch within 1–2 weeks; others should follow within 4 weeks as part of routine firmware refresh cycles.

Risk score, explained

CVSS v3.1 score of 7.1 (HIGH) reflects: Attack Vector=Local (limits initial access but assumes compromise in REE), Attack Complexity=Low (straightforward to exploit once access is gained), Privileges Required=None (no special privilege needed to call vulnerable wrappers), User Interaction=None (no user action required), Scope=Changed (TEE breach affects other components/trust zones), Confidentiality Impact=High (direct secret leakage), Integrity Impact=None (data is read, not modified), Availability Impact=None. This score appropriately weights the isolation-boundary break and secret disclosure against the local-access requirement.

Frequently asked questions