CVE-2026-41514: OP-TEE Hisilicon RSA-OAEP Padding Oracle

Technical summary

The Hisilicon HPRE crypto driver in OP-TEE versions 4.5.0 through 4.10.x implements RSA-OAEP decryption with a timing-oracle vulnerability. During label hash verification, the code uses non-constant-time memcmp() and exposes multiple distinguishable error paths that leak information about decryption success or failure. An attacker performing adaptive chosen-ciphertext queries can exploit this Manger-style padding oracle to recover plaintext with approximately 1000–2000 queries. The vulnerability is constrained to the plat-d06 platform with CFG_HISILICON_ACC_V3 enabled—a non-default configuration. Version 4.11.0 patches the issue.

Business impact

The impact is limited to organizations running OP-TEE on Hisilicon-equipped Arm platforms with the optional accelerator driver explicitly enabled. For most users, this vulnerability presents no risk since the driver is disabled by default. For affected deployments handling sensitive RSA-encrypted data in a TEE, an attacker with local system access could potentially recover encrypted secrets through sustained cryptographic side-channel attacks. Real-world exploitation requires either misconfiguration or deliberate enablement of the driver for performance reasons.

Affected systems

OP-TEE versions 4.5.0 through 4.10.x running on plat-d06 (Hisilicon platform) with CFG_HISILICON_ACC_V3=y. The vulnerability does not affect: other OP-TEE versions, non-Hisilicon platforms, or any deployment with the default configuration (CFG_HISILICON_ACC_V3=n). Users should verify their platform name and build configuration to determine exposure.

Exploitability

Exploitation requires local system access, making it a privilege boundary attack. An attacker must send 1000–2000 carefully constructed RSA-OAEP ciphertexts to the TEE and observe timing or error responses to extract plaintext. The attack is feasible but not trivial; it demands cryptographic sophistication and sustained interaction. The CVSS score of 2.5 (LOW) reflects the combination of local-only access requirement, high attack complexity, and limited information disclosure.

Remediation

Update OP-TEE to version 4.11.0 or later. Alternatively, disable the Hisilicon accelerator by setting CFG_HISILICON_ACC_V3=n at build time. Organizations not using Hisilicon hardware or running default OP-TEE builds are not affected and require no action. Rebuilding OP-TEE with the patched version is straightforward for most embedded deployments.

Patch guidance

Apply OP-TEE 4.11.0 or a later maintenance release. Verify the patch by checking the version string reported by OP-TEE at runtime or via your build system. If rebuilding is impractical, the workaround of setting CFG_HISILICON_ACC_V3=n during compilation is effective and has no functional impact on standard deployments. Consult your OP-TEE distribution or vendor for backported patches to earlier LTS branches if applicable.

Detection guidance

Review your OP-TEE build configuration files (typically in the device tree or board makefile) for any reference to CFG_HISILICON_ACC_V3=y. Check OP-TEE version by querying TEE properties through the TEE Client API or examining firmware logs. Monitor for unusual patterns of RSA decryption requests from untrusted sources, though such monitoring in a TEE environment is limited. If Hisilicon acceleration is not needed, disabling it eliminates the risk entirely.

Why prioritize this

This vulnerability merits low priority for most organizations due to its default-disabled configuration and local-access-only requirement. Prioritize patching only if you explicitly enable the Hisilicon driver or run OP-TEE on Hisilicon platforms with hardware acceleration. Verify your build configuration before allocating remediation resources; many teams will find they are unaffected.

Risk score, explained

CVSS 2.5 (LOW) reflects the combination of: local attack vector (AV:L), high attack complexity requiring 1000–2000 queries and cryptographic skill (AC:H), and limited impact—confidentiality only, no integrity or availability loss (C:L/I:N/A:N). The score is not elevated by default-disabled status, but that significantly reduces practical risk. Organizations running the vulnerable configuration face meaningful risk; others face none.

Frequently asked questions