# CVE-2021-27562: Arm Trusted Firmware Out-of-Bounds Write Vulnerability

Source: https://junglewise.ai/threats/cve-2021-27562-arm-trusted-firmware-out-of-bounds-write-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-27562 · Severity: critical · CVSS 5.5 · Exploited in the wild · Published 2021-11-03

Arm Trusted Firmware-M contains an out-of-bounds write vulnerability when calling secure functions under the Non-Secure Processing Environment (NSPE) handler mode. A local attacker in the non-secure world can exploit this to trigger a system halt, overwrite secure data, or leak secure information.

Vendors: [Arm](https://junglewise.ai/threats/vendors/arm).

## Quick answers

**Is CVE-2021-27562 exploited in the wild?** Yes. CVE-2021-27562 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2021-27562?** Critical severity, with a CVSS score of 5.5, published 3 November 2021.

**Which products and versions are affected?** Arm Trusted Firmware-M up to and including 1.2.0; Yealink Device Management Server.

**Is there a fix for CVE-2021-27562?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-27562 attacked?** It is attacked with local access, in device firmware.

**Am I affected by CVE-2021-27562?** Check whether you run Arm Trusted Firmware. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Arm Trusted Firmware-M up to and including 1.2.0
- Yealink Device Management Server

## Timeline

- 2021-05-25: disclosed: NVD Published Date
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2021-11-03: other: Advisory published date provided in report

## Related threats

- [ARM Trusted Firmware Secure world register state leak in Trusty context switch](https://junglewise.ai/threats/cve-2026-59580-in-trusty-context-switch-of-services-spd-trusty-trusty-c-there-is)