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Vulnerability record · CVE-2020-12638 · published 23 July 2020

CVE-2020-12638: Espressif esp-idf improper authentication vulnerability

EEspressif · Esp Idf

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.

6.8 CVSS 3.1 Medium EPSS 0.45% · top 62.7% CWE-287 · Improper authenticationCWE-319 · Cleartext transmission
6.8CVSS 3.1 base score, v2 4.3
0.45%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
8References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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.

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

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/espressif/ESP8266_NONOS_SDK Third Party Advisory
https://github.com/espressif/ESP8266_RTOS_SDK Third Party Advisory
https://github.com/espressif/esp-idf Third Party Advisory
https://lbsfilm.at/blog/wpa2-authenticationmode-downgrade-in-espressif-microprocessors ExploitPatchThird Party Advisory
https://github.com/espressif/ESP8266_NONOS_SDK Third Party Advisory
https://github.com/espressif/ESP8266_RTOS_SDK Third Party Advisory
https://github.com/espressif/esp-idf Third Party Advisory
https://lbsfilm.at/blog/wpa2-authenticationmode-downgrade-in-espressif-microprocessors ExploitPatchThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2020-12638), CISA KEV, FIRST EPSS (scores of 2026-10-12). This page is refreshed as NVD updates the record.