CVE-2020-6808Public exploitNetwork attack vector

URL spoofing via incorrect JavaScript document origin

Published Mar 25, 2020 · Updated Aug 4, 2024

URL spoofing in Mozilla Firefox before 74 allows remote attackers to misrepresent a page's origin through a crafted JavaScript URL. When a javascript: URL returns a string, Firefox parses it into an HTML document but exposes the javascript: URL instead of the originating document's URL through document.location and browser history. Exploitation requires a user to open the crafted content and navigate back, allowing the displayed URL to mislead the user about the active document's origin without reading data or interrupting the browser.

CVSS severity6.5
Medium
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL spoofing in Mozilla Firefox before 74 allows remote attackers to misrepresent a page's origin through a crafted JavaScript URL. When a javascript: URL returns a string, Firefox parses it into an HTML document but exposes the javascript: URL instead of the originating document's URL through document.location and browser history. Exploitation requires a user to open the crafted content and navigate back, allowing the displayed URL to mislead the user about the active document's origin without reading data or interrupting the browser.

The record

CVE
CVE-2020-6808
Published
Mar 25, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-290
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 25, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <74

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <74

Published CVSS scores

6.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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