Cyber Resilience

CVE-2025-27840

Espressif Esp32 Firmware

Public PoC
Published
08 March 2025
Modified
12 March 2025
Patch / advisory
View advisory
CVSS Score v3.1 6.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:P/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L
EPSS Score 0.013 69th percentile
Risk Priority 51 floored blend · peak EPSS

Summary

CVE-2025-27840 is a medium-severity Hidden Functionality (CWE-912) vulnerability in Espressif Esp32 Firmware. Its CVSS base score is 6.8 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Redundant Access (T1108); ranked in the top 31% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to CM-2 (Baseline Configuration) and CM-7 (Least Functionality) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Espressif ESP32 chips allow 29 hidden HCI commands, such as 0xFC02 (Write memory).

CWE(s)
CWE-912NVD-CWE-Other

Related Threats

MITRE ATT&CK Enterprise Techniques

T1108 Redundant Access Stealth
**This technique has been deprecated.
attack.mitre.org →
T1505 Server Software Component Persistence
Adversaries may abuse legitimate extensible development features of servers to establish persistent access to systems.
attack.mitre.org →
T1505.003 Web Shell Persistence
Adversaries may backdoor web servers with web shells to establish persistent access to systems.
attack.mitre.org →
T1554 Compromise Host Software Binary Persistence
Adversaries may modify host software binaries to establish persistent access to systems.
attack.mitre.org →
T1195 Supply Chain Compromise Initial Access
Adversaries may manipulate products or product delivery mechanisms prior to receipt by a final consumer for the purpose of data or system compromise.
attack.mitre.org →
T1195.002 Compromise Software Supply Chain Initial Access
Adversaries may manipulate application software prior to receipt by a final consumer for the purpose of data or system compromise.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-11673Shared CWE-912
CVE-2026-14812Shared CWE-912
CVE-2026-61515Shared CWE-912
CVE-2023-25183Shared CWE-912
CVE-2023-4467Shared CWE-912
CVE-2024-37994Shared CWE-912
CVE-2026-4621Shared CWE-912
CVE-2026-18191Shared CWE-912
CVE-2025-2894Shared CWE-912
CVE-2024-39754Shared CWE-912

Affected Assets

espressif
esp32 firmware
all versions

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

CM-2 Baseline Configuration good match

Maintaining and reviewing a documented baseline configuration allows comparison that reveals any functionality absent from the approved specification.

CM-7 Least Functionality good match

Least-functionality configuration explicitly prohibits or restricts any capability not required by the approved baseline, blocking hidden additions.

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation activities are designed to discover undocumented or unspecified functionality after it has been introduced.

SA-15 Development Process, Standards, and Tools partial match

Documented development processes and standards require all functionality to be specified and visible, structurally preventing undocumented hidden features.

SA-3 System Development Life Cycle partial match

An SDLC that incorporates security engineering principles mandates that all product functions be part of the approved specification.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 full match
prevents

Secure SDLC practices directly prevent introduction of undocumented hidden functionality during development.

ID.RA-09 mostly match
prevents

Pre-acquisition integrity/authenticity checks can detect undocumented hidden functions in supplied software/hardware.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance can discover undocumented functionality before release.

A.8.32 Change management mostly match
prevents

Change management processes can catch unauthorized additions but do not inherently prevent hidden functionality from being introduced.

A.8.16 Monitoring activities partial match
finds

Monitoring activities can detect anomalous behavior from hidden functions but do not eliminate the weakness.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates documented requirements and design reviews that would expose undocumented hidden functionality.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly define expected functionality, making hidden features a violation.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles require transparent, documented designs that preclude hidden functionality.

References