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TI-2020-09927 Aliases CVE-2020-12409GHSA-j545-cjf3-8m8v

When using certain blank characters in a URL, they where incorrectly rendered as spaces…

Priority MEDIUM 40Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

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

Why it matters now

EPSS 0.01178 67th percentileScored 2026-11-07
Fix Fixed Firefox (Mozilla): 77

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaFirefoxbefore 7777Patch availableCNA
  • Firefox VendorMozilla Affected before 77 Fixed in 77 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 77.0VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 77.0 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Firefox (Mozilla) Fixed in 77

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Mozilla Firefox 77

    4 records Highest priority Priority MEDIUM 2 MEDIUM, 2 LOW

    Other records, highest priority first

    • TI-2020-09929 Out-of-bounds write in Mozilla FirefoxPriority MEDIUM 40
    • TI-2020-09926 When browsing a document hosted on an IP address, an attacker could insert certain…Priority LOW 31
    • TI-2020-09925 Out-of-bounds read in Mozilla FirefoxPriority LOW 31
    Show all 4 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-12409
  2. 2026-10-03 Alias added: GHSA-j545-cjf3-8m8v

References

Advisory 2

  • TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
  • TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
  • TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
  • TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
See all 3444 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences