CVE-2020-35111

4.3 mediumEPSS 1.4%

Medium (4.3) in mozilla. EPSS 1.4% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

4.3 medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

EPSS: 1.4% chance of exploitation in the next 30 days; higher than 73% of CVEs (scores of 2026-10-31)
Published: 2021-01-07
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:firefox_esr
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1657916
https://www.mozilla.org/security/advisories/mfsa2020-54/
https://www.mozilla.org/security/advisories/mfsa2020-55/
https://www.mozilla.org/security/advisories/mfsa2020-56/
https://bugzilla.mozilla.org/show_bug.cgi?id=1657916

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