For native-to-JS bridging the app requires a unique token to be passed that ensures non-app code can't call the bridging functions.

published 2020-07-09 6y ago modified 2026-08-19 2mo ago also EUVD-2020-4716

cvss: 4.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.8%; EPSS 0.8% chance of exploitation in 30 days, percentile 56%
public exploits: 0; none known

For native-to-JS bridging the app requires a unique token to be passed that ensures non-app code can't call the bridging functions. That token could leak when used for downloading files. This vulnerability affects Firefox for iOS < 26.

Patch / fix

fixed in 1

Mozilla Firefox for iOS 26

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Exploit prediction

0.79% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 for iOS

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

mozilla.org /security/advisories/mfsa2020-19/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1631739
issue-tracking, permissions-required, vendor-advisory

Sources

CVE List CVE-2020-12404
NVD CVE-2020-12404

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