CVE-2026-33662: CWE-190: Integer Overflow or Wraparound in OP-TEE optee_os
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 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.
AI Analysis
Technical Summary
OP-TEE, a Trusted Execution Environment for Arm Cortex-A cores using TrustZone, contains an integer overflow vulnerability (CWE-190) in versions 3.8.0 to 4.10. The flaw exists in the emsa_pkcs1_v1_5_encode() function within the RSA signature padding implementation. When a small modulus is selected, the calculation of the padding size (PS size) subtracts the digest and other fields from the modulus size, which can overflow and underflow the integer. This causes memset() to overwrite memory beyond intended bounds, resulting in a crash of the OP-TEE environment. This vulnerability only affects platforms that register RSA acceleration.
Potential Impact
The vulnerability leads to a denial of service condition by crashing the OP-TEE environment due to memory overwrite caused by an integer underflow in padding calculation. There is no impact on confidentiality or integrity according to the CVSS vector. The availability of the affected system is compromised, which could disrupt services relying on OP-TEE's secure execution.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround is currently documented. Until a patch is available, avoid using affected OP-TEE versions (3.8.0 to 4.10) on platforms with RSA acceleration enabled or restrict usage scenarios that involve small RSA modulus values triggering the overflow.
CVE-2026-33662: CWE-190: Integer Overflow or Wraparound in OP-TEE optee_os
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. 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 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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
OP-TEE, a Trusted Execution Environment for Arm Cortex-A cores using TrustZone, contains an integer overflow vulnerability (CWE-190) in versions 3.8.0 to 4.10. The flaw exists in the emsa_pkcs1_v1_5_encode() function within the RSA signature padding implementation. When a small modulus is selected, the calculation of the padding size (PS size) subtracts the digest and other fields from the modulus size, which can overflow and underflow the integer. This causes memset() to overwrite memory beyond intended bounds, resulting in a crash of the OP-TEE environment. This vulnerability only affects platforms that register RSA acceleration.
Potential Impact
The vulnerability leads to a denial of service condition by crashing the OP-TEE environment due to memory overwrite caused by an integer underflow in padding calculation. There is no impact on confidentiality or integrity according to the CVSS vector. The availability of the affected system is compromised, which could disrupt services relying on OP-TEE's secure execution.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround is currently documented. Until a patch is available, avoid using affected OP-TEE versions (3.8.0 to 4.10) on platforms with RSA acceleration enabled or restrict usage scenarios that involve small RSA modulus values triggering the overflow.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-23T15:23:42.219Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69ebb81d87115cfb68646f6d
Added to database: 4/24/2026, 6:36:13 PM
Last enriched: 4/24/2026, 6:51:24 PM
Last updated: 4/25/2026, 4:56:22 AM
Views: 10
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