# CVE-2026-71969: OP-TEE OS 4.10.0 Buffer Underwrite via RSA NOPAD Encrypt/Decrypt Operations

Status: published. Published: 2026-08-10. Updated: 2026-11-08.

OP-TEE OS through 4.10.0, fixed in commit 7b8b494, contains a buffer underwrite vulnerability in the RSA NOPAD encrypt and decrypt operations within the mbedTLS software backend and SE050 hardware driver that allows a malicious Trusted Application to corrupt secure-world heap memory by supplying an input length exceeding the RSA modulus size. When src_len exceeds rsa_len, the subtraction expression wraps to a large unsigned value, causing a subsequent memcpy to write attacker-controlled data before the destination buffer in S-EL1 secure-world heap memory.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/OP-TEE/optee_os/pull/7898
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/OP-TEE/optee_os/pull/7808
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/OP-TEE/optee_os/commit/7b8b494e0a324cefec8ed386b7de413b44f1aaf3

## Affected products and versions

- OP-TEE / optee_os (OP-TEE/optee_os): ≥ 0; ≤ 4.10.0 (affected, semver); 7b8b494e0a324cefec8ed386b7de413b44f1aaf3 (unaffected, git). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.4 (high); CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 6.7 (medium); CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.18% as of 2026-11-08; percentile 7.89%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-787, CWE-124

## Exploit evidence

- exploit: https://blog.secmate.dev/posts/optee-vulnerabilities-disclosure/ (CNA: VulnCheck)

## References

- https://blog.secmate.dev/posts/optee-vulnerabilities-disclosure/ (CNA: VulnCheck; technical-description, exploit)

- https://github.com/OP-TEE/optee_os/pull/7898 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/OP-TEE/optee_os/pull/7808 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/OP-TEE/optee_os/commit/7b8b494e0a324cefec8ed386b7de413b44f1aaf3 (CNA: VulnCheck; patch)

- https://www.vulncheck.com/advisories/op-tee-os-buffer-underwrite-via-rsa-nopad-encrypt-decrypt-operations (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-71969; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-71969; retrieved 2026-11-08; source updated Not reported

Revision: 7a0a3ce264202347052d2d889ba23af090f187a54010db2bdd468a3528ea1f90

Canonical: https://y2.dev/cve/CVE-2026-71969

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