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TI-2026-26042 Aliases CVE-2026-33662

OP-TEE: RSASSA EMSA- PKCS1-v1_5 underflow in emsa_pkcs1_v1_5_encode()

Priority LOW 39CWE-190Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-190 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00403 34th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
OP-TEEoptee_os3.8.0 – 4.10—No fix listedCNA
  • optee_os VendorOP-TEE Affected 3.8.0 – 4.10 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:trustedfirmware:op-tee:*:*:*:*:*:*:*:*3.8.0 – 4.10.0VulnerableOP-TEE
  • cpe:2.3:o:trustedfirmware:op-tee:*:*:*:*:*:*:*:* Versions 3.8.0 – 4.10.0 Vulnerable ·OP-TEE

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33662
  2. 2026-10-25 Priority changed: MEDIUM → LOW

References

Patch 1

  • TI-2022-22796 OP-TEE Trusted OS vulnerable to Improper Validation of Array Index in the cleanup_shm_refs function CVSS 3.1HIGH 8.8
  • TI-2026-29072 OP-TEE has a Use-After-Free race in FF-A shared-memory teardown CVSS 3.1HIGH 7.8
  • TI-2023-21925 OP-TEE double free in shdr_verify_signature CVSS 3.1HIGH 7.4
  • TI-2026-33359 OP-TEE vulnerable to ECDH private key recovery CVSS 3.1MEDIUM 4.7
  • TI-2019-16063 Integer overflow in OP-TEE CVSS 3.0CRITICAL 9.8
  • TI-2019-16062 Integer overflow in OP-TEE CVSS 3.0CRITICAL 9.8
See all 28 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences