Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2026-33662 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Trustedfirmware Op-Tee. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 33th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-33662 is an integer overflow vulnerability (CWE-190) in OP-TEE, a Trusted Execution Environment designed to accompany a non-secure Linux kernel on Arm Cortex-A cores utilizing TrustZone technology. The issue affects versions 3.8.0 through 4.10 and is located in the emsa_pkcs1_v1_5_encode() function within core/drivers/crypto/crypto_api/acipher/rsassa.c. There, the padding size ("PS size") is computed by subtracting the digest size and other fixed fields from the RSA key's modulus size; a sufficiently small modulus causes this subtraction to overflow, resulting in an underflowed value passed to memset() for padding with 0xFF bytes. This triggers excessive memory overwrites, crashing OP-TEE. The flaw only impacts platforms that register RSA acceleration.
With a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), the vulnerability enables remote attackers with network access to exploit it without authentication, privileges, or user interaction. By supplying a crafted RSA key featuring a small modulus during an RSA operation that invokes the vulnerable encoding function, an attacker can induce the integer underflow, leading to OP-TEE denial of service via crash and potential disruption of secure operations.
Mitigation details are available in the OP-TEE GitHub security advisory at https://github.com/OP-TEE/optee_os/security/advisories/GHSA-4cf8-v5g3-73gr.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25592
Vulnerability Data
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. From 3.8.0 to 4.10, in the function emsa_pkcs1_v1_5_encode() in core/drivers/crypto/crypto_api/acipher/rsassa.c, the amount of padding needed, "PS…
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size", is calculated by subtracting the size of the digest and other fields required for the EMA-PKCS1-v1_5 encoding from the size of the modulus of the key. By selecting a small enough modulus, this subtraction can overflow. The padding is added as a string of 0xFF bytes with a call to memset(), and an underflowed integer will cause the memset() call to overwrite until OP-TEE crashes. This only affects platforms registering RSA acceleration.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.2.6
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds integer overflow defects before deployment.
Secure engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer overflow during calculation.
Input validation enforces bounds on values before arithmetic, stopping the conditions that trigger overflow or wraparound.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect integer overflows before release.
Secure SDLC mandates input validation and arithmetic checks that prevent integer overflows.
Application security requirements include bounds checking and safe arithmetic to avoid overflow conditions.
Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.
Secure coding standards explicitly forbid unsafe integer operations and mandate overflow-safe constructs.