# CVE-2026-71967: OP-TEE OS 4.10.0 NULL Pointer Dereference DoS via Widevine PTA open_session

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

OP-TEE OS through 4.10.0, fixed in commit 0aadfc2, contains a null pointer dereference vulnerability in the Widevine pseudo-TA open_session handler that allows Normal World clients to cause a denial of service when CFG_WIDEVINE_PTA is enabled. Attackers can open a session directly on the Widevine PTA to trigger an unconditional dereference of a NULL calling session pointer via is_user_ta_ctx(), faulting the TEE at S-EL1 and crashing the trusted execution environment.

## 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/7899
- 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/0aadfc23407f50e770eb5ddd871fc208f5626833

## Affected products and versions

- OP-TEE / optee_os (OP-TEE/optee_os): ≥ 0; ≤ 4.10.0 (affected, semver); 0aadfc23407f50e770eb5ddd871fc208f5626833 (unaffected, git). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.7 (medium); CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.17% as of 2026-11-08; percentile 6.39%

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

- Weaknesses: CWE-476

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/OP-TEE/optee_os/pull/7899 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/OP-TEE/optee_os/commit/0aadfc23407f50e770eb5ddd871fc208f5626833 (CNA: VulnCheck; patch)

- https://www.vulncheck.com/advisories/op-tee-os-null-pointer-dereference-dos-via-widevine-pta-open-session (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-71967; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-71967; retrieved 2026-11-08; source updated Not reported

Revision: 99d8754679c2bb8fa55bc2af8a125b3adf3b8dee7f72a6050ac42e97ff1c3de4

Canonical: https://y2.dev/cve/CVE-2026-71967

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