What’s Vulnerable › Vulnerabilities

CVE-2020-12409

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-09 · updated 2026-06-17

Description

When using certain blank characters in a URL, they where incorrectly rendered as spaces instead of an encoded URL. This vulnerability affects Firefox < 77.

Affected products

• Mozilla Firefox: before 77.0 — fixed in 77.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 77.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1629506
• https://www.mozilla.org/security/advisories/mfsa2020-20/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1629506
• https://www.mozilla.org/security/advisories/mfsa2020-20/

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