CVE-2021-43531

low-risk

Published 2021-12-08

When a user loaded a Web Extensions context menu, the Web Extension could access the post-redirect URL of the element clicked. If the Web Extension lacked the WebRequest permission for the hosts involved in the redirect, this would be a same-origin-violation leaking data the Web Extension should have access to. This was fixed to provide the pre-redirect URL. This is related to CVE-2021-43532 but in the context of Web Extensions. This vulnerability affects Firefox < 94.

Do I need to act?

0.08% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 4.3/10 Medium

NETWORK / LOW complexity

Affected Products (1)

Firefox

Affected Vendors

Mozilla

References (4)

Issue Tracking https://bugzilla.mozilla.org/show_bug.cgi?id=1659155

Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2021-48/

Issue Tracking https://bugzilla.mozilla.org/show_bug.cgi?id=1659155

Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2021-48/

/ 100

low-risk

Severity 18/34 · Moderate

Exploitability 0/34 · Minimal

Exposure 5/34 · Minimal