CVE-2020-15664

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-10-01 · updated 2026-08-19
Weakness: CWE-863

Description

By holding a reference to the eval() function from an about:blank window, a malicious webpage could have gained access to the InstallTrigger object which would allow them to prompt the user to install an extension. Combined with user confusion, this could result in an unintended or malicious extension being installed. This vulnerability affects Firefox < 80, Thunderbird < 78.2, Thunderbird < 68.12, Firefox ESR < 68.12, Firefox ESR < 78.2, and Firefox for Android < 80.

Affected products

Mozilla Firefox: before 80.0; from 78.0 before 78.2 — fixed in 78.2, 80.0
Mozilla Firefox ESR: before 68.12 — fixed in 68.12
Mozilla Firefox for Android: before 80.0 — fixed in 80.0
Mozilla Thunderbird: before 68.12; from 78.0 before 78.2 — fixed in 68.12, 78.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 78.2, 80.0; Mozilla Firefox ESR 68.12; Mozilla Firefox for Android 80.0; Mozilla Thunderbird 68.12, 78.2. Check the vendor advisory for mitigations.

References

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