CVE-2020-15658

Name: CVE-2020-15658
Creator: NVD / NIST
Published: 2020-08-10T18:15:12.653+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.20%

Last modified Jun 17, 2026

CVE-2020-15658 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. The code for downloading files did not properly take care of special characters, which led to an attacker being able to cut off the file ending at an earlier position, leading to a different file type being downloaded than shown in the dialog. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.. EPSS estimates a 1.20% chance of exploitation in the next 30 days.

Description

The code for downloading files did not properly take care of special characters, which led to an attacker being able to cut off the file ending at an earlier position, leading to a different file type being downloaded than shown in the dialog. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.20%

64.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-754

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 79.0
Mozilla	Firefox Esr	< 78.1
Mozilla	Thunderbird	< 78.1
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	20.04

References

http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1637745Issue Tracking, Permissions Required, Vendor Advisory
https://usn.ubuntu.com/4443-1/Third Party 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=1637745Issue Tracking, Permissions Required, Vendor Advisory
https://usn.ubuntu.com/4443-1/Third Party 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-2020-15658?

How severe is CVE-2020-15658?

CVE-2020-15658 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.20% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15658?

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-2020-15658?

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

Scan your code now

Source: NVD / NIST