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CVE-2021-38502 Moderate

CVE-2021-38502

Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection. A MITM could perform a downgrade attack to intercept transmitted messages, or could take control of the authenticated session to execute SMTP commands chosen by the MITM. If an unprotected authentication method was configured, the MITM could obtain the authentication credentials, too. This vulnerability affects Thunderbird < 91.2.

Exploit probability 1.1%
Published November 3, 2021
Required by Not available
Last source change April 16, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities CVE-2021-38502

Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection. A MITM could perform a downgrade attack to intercept transmitted messages, or could take control of the authenticated session to execute SMTP commands chosen by the MITM. If an unprotected authentication method was configured, the MITM could obtain the authentication credentials, too. This vulnerability affects Thunderbird < 91.2.

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05 / REFERENCES

Further evidence