CVE-2020-35111
While web content cannot navigate to such URLs, a user opening View Source could have inadvertently leaked their IP address.
Does this matter?
Lower severity and a low EPSS score (1.43%). Track it; it rarely justifies an emergency change on its own.
Description
When an extension with the proxy permission registered to receive <all_urls>, the proxy.onRequest callback was not triggered for view-source URLs. While web content cannot navigate to such URLs, a user opening View Source could have inadvertently leaked their IP address. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.
- CVSS 3.1
- 4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
- EPSS
- 1.43% probability · 73th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 1.4% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1657916Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2020-54/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-55/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-56/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1657916Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2020-54/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-55/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2020-56/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.