CVE-2020-12638

Name: CVE-2020-12638
Creator: NVD / NIST
Published: 2020-07-23T16:15:12.49+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.8/10EPSS 0.47%

Last modified Jun 17, 2026

CVE-2020-12638 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. An encryption-bypass issue was discovered on Espressif ESP-IDF devices through 4.2, ESP8266_NONOS_SDK devices through 3.0.3, and ESP8266_RTOS_SDK devices through 3.3. Broadcasting forged beacon frames forces a device to change its authentication mode to OPEN, effectively disabling its 802.11 encryption.. EPSS estimates a 0.47% chance of exploitation in the next 30 days.

Description

An encryption-bypass issue was discovered on Espressif ESP-IDF devices through 4.2, ESP8266_NONOS_SDK devices through 3.0.3, and ESP8266_RTOS_SDK devices through 3.3. Broadcasting forged beacon frames forces a device to change its authentication mode to OPEN, effectively disabling its 802.11 encryption.

Metrics

CVSS 3.1

6.8/10

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

0.47%

37.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Espressif	Esp-Idf	<= 4.2
Espressif	Esp8266 Nonos Sdk	<= 3.0.3
Espressif	Esp8266 Rtos Sdk	<= 3.3

References

https://github.com/espressif/ESP8266_NONOS_SDKThird Party Advisory
https://github.com/espressif/ESP8266_RTOS_SDKThird Party Advisory
https://github.com/espressif/esp-idfThird Party Advisory
https://lbsfilm.at/blog/wpa2-authenticationmode-downgrade-in-espressif-microprocessorsExploit, Patch, Third Party Advisory
https://github.com/espressif/ESP8266_NONOS_SDKThird Party Advisory
https://github.com/espressif/ESP8266_RTOS_SDKThird Party Advisory
https://github.com/espressif/esp-idfThird Party Advisory
https://lbsfilm.at/blog/wpa2-authenticationmode-downgrade-in-espressif-microprocessorsExploit, Patch, Third Party Advisory

Timeline

Published: Jul 23, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-12638?

How severe is CVE-2020-12638?

CVE-2020-12638 has a CVSS score of 6.8/10 (MEDIUM severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12638?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-12638?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST