CVE-2021-43531 json
When a user loaded a Web Extensions context menu, the Web Extension could access the post-redirect URL of the element clicked.
published 2021-12-08 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-30460
- cvss
- 4.3
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 27%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- Mozilla Firefox 94
Exploit prediction
0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 4.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:P/I:N/A:N |
Affected products
- Mozilla Firefox
Classification
- Weakness
-
- CWE-346 Origin Validation Error
References
-
mozilla.org
/security/advisories/mfsa2021-48/
vendor-advisory
-
bugzilla.mozilla.org
/show_bug.cgi?id=1659155
issue-tracking, permissions-required, vendor-advisory
Sources
- CVE List CVE-2021-43531
- NVD CVE-2021-43531
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