CVE-2020-15657

Name: CVE-2020-15657
Creator: NVD / NIST
Published: 2020-08-10T18:15:12.593+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.35%

Last modified Jun 17, 2026

CVE-2020-15657 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. Firefox could be made to load attacker-supplied DLL files from the installation directory. This required an attacker that is already capable of placing files in the installation directory. EPSS estimates a 0.35% chance of exploitation in the next 30 days.

Description

Firefox could be made to load attacker-supplied DLL files from the installation directory. This required an attacker that is already capable of placing files in the installation directory. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.35%

27.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-427

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 79.0
Mozilla	Firefox Esr	< 78.1
Mozilla	Thunderbird	< 78.1

References

http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1644954Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-32/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-33/Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1644954Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-32/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-33/Vendor Advisory

Timeline

Published: Aug 10, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15657?

How severe is CVE-2020-15657?

CVE-2020-15657 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.35% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15657?

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-2020-15657?

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

Scan your code now

Source: NVD / NIST