CVE-2020-26958

MEDIUM

Firefox < 83.0, Firefox ESR < 78.5, and Thunderbird < 78.5 - Cross-Site Scripting via ServiceWorker Cached Response

Title source: llm
STIX 2.1

Description

Firefox did not block execution of scripts with incorrect MIME types when the response was intercepted and cached through a ServiceWorker. This could lead to a cross-site script inclusion vulnerability, or a Content Security Policy bypass. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

References (4)

Core 4
Core References
Issue Tracking, Permissions Required, Vendor Advisory x_refsource_misc
https://bugzilla.mozilla.org/show_bug.cgi?id=1669355
Vendor Advisory x_refsource_confirm
https://www.mozilla.org/security/advisories/mfsa2020-50/
Vendor Advisory x_refsource_confirm
https://www.mozilla.org/security/advisories/mfsa2020-52/
Vendor Advisory x_refsource_confirm
https://www.mozilla.org/security/advisories/mfsa2020-51/

Scores

CVSS v3 6.1
EPSS 0.0046
EPSS Percentile 64.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Details

CWE
CWE-79
Status published
Products (3)
mozilla/firefox < 83.0
mozilla/firefox_esr < 78.5
mozilla/thunderbird < 78.5
Published Dec 09, 2020
Tracked Since Feb 18, 2026