CVE-2020-15646

Name: CVE-2020-15646
Creator: NVD / NIST
Published: 2020-10-08T14:15:12.483+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.9/10EPSS 0.95%

Last modified Jun 17, 2026

CVE-2020-15646 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. If an attacker intercepts Thunderbird's initial attempt to perform automatic account setup using the Microsoft Exchange autodiscovery mechanism, and the attacker sends a crafted response, then Thunderbird sends username and password over https to a server controlled by the attacker. This vulnerability affects Thunderbird < 68.10.0.. EPSS estimates a 0.95% chance of exploitation in the next 30 days.

Description

If an attacker intercepts Thunderbird's initial attempt to perform automatic account setup using the Microsoft Exchange autodiscovery mechanism, and the attacker sends a crafted response, then Thunderbird sends username and password over https to a server controlled by the attacker. This vulnerability affects Thunderbird < 68.10.0.

Metrics

CVSS 3.1

5.9/10

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

EPSS Probability

0.95%

56.7th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mozilla	Thunderbird	< 68.10.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1606610Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-26/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1606610Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-26/Vendor Advisory

Timeline

Published: Oct 8, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15646?

How severe is CVE-2020-15646?

CVE-2020-15646 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.95% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15646?

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-2020-15646?

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

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Source: NVD / NIST