CVE-2020-15659

Name: CVE-2020-15659
Creator: NVD / NIST
Published: 2020-08-10T18:15:12.7+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 2.40%

Last modified Jun 17, 2026

CVE-2020-15659 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Mozilla developers and community members reported memory safety bugs present in Firefox 78 and Firefox ESR 78.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. EPSS estimates a 2.40% chance of exploitation in the next 30 days.

Description

Mozilla developers and community members reported memory safety bugs present in Firefox 78 and Firefox ESR 78.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 79, Firefox ESR < 68.11, Firefox ESR < 78.1, Thunderbird < 68.11, and Thunderbird < 78.1.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

2.40%

81.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 79.0
Mozilla	Firefox Esr	< 68.11
Mozilla	Firefox Esr	>= 78.0, < 78.1.0
Mozilla	Thunderbird	< 68.11
Mozilla	Thunderbird	>= 78.0.1, < 78.1.0
Opensuse	Leap	15.1
Opensuse	Leap	15.2
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/msg00022.htmlMailing List, Patch, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlMailing List, Patch, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00032.htmlMailing List, Patch, Third Party Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1550133%2C1633880%2C1643613%2C1644839%2C1645835%2C1646006%2C1646787%2C1649347%2C1650811%2C1651678Issue Tracking, Permissions Required, Vendor Advisory
https://usn.ubuntu.com/4443-1/Patch, Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-31/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-32/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-33/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-35/Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00022.htmlMailing List, Patch, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlMailing List, Patch, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00032.htmlMailing List, Patch, Third Party Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1550133%2C1633880%2C1643613%2C1644839%2C1645835%2C1646006%2C1646787%2C1649347%2C1650811%2C1651678Issue Tracking, Permissions Required, Vendor Advisory
https://usn.ubuntu.com/4443-1/Patch, Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-31/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-32/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-33/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-35/Vendor Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2020-15659?

How severe is CVE-2020-15659?

CVE-2020-15659 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 2.40% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15659?

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-2020-15659?

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

Scan your code now

Source: NVD / NIST