What’s Vulnerable › Vulnerabilities

CVE-2020-15659

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-08-10 · updated 2026-06-17
• Weakness: CWE-787

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.

Affected products

• Canonical Ubuntu Linux: 16.04, 18.04, 20.04
• Mozilla Firefox: before 79.0 — fixed in 79.0
• Mozilla Firefox ESR: before 68.11; from 78.0 before 78.1.0 — fixed in 68.11, 78.1.0
• Mozilla Thunderbird: before 68.11; from 78.0.1 before 78.1.0 — fixed in 68.11, 78.1.0
• openSUSE Leap: 15.1, 15.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 79.0; Mozilla Firefox ESR 68.11, 78.1.0; Mozilla Thunderbird 68.11, 78.1.0. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00022.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00032.html
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=1550133%2C1633880%2C1643613%2C1644839%2C1645835%2C1646006%2C1646787%2C1649347%2C1650811%2C1651678
• https://usn.ubuntu.com/4443-1/
• https://www.mozilla.org/security/advisories/mfsa2020-30/
• https://www.mozilla.org/security/advisories/mfsa2020-31/
• https://www.mozilla.org/security/advisories/mfsa2020-32/
• https://www.mozilla.org/security/advisories/mfsa2020-33/
• https://www.mozilla.org/security/advisories/mfsa2020-35/
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00022.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.html

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