CVE-2020-26958

Mozilla: Requests intercepted through ServiceWorkers lacked MIME type restrictions

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Severity

Moderate

Red Hat Product Security

6.1

CVSS 3.0

Review impact separately from score.

Published · November 17, 2020

Updated · November 22, 2025

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.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.0 · 6.1
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')