CVE-2023-6211Public exploitNetwork attack vector

HTTP downgrade via clickjacked HTTPS-Only exception

Published Nov 21, 2023 · Updated Feb 13, 2025

Clickjacking in Mozilla Firefox before 120 allows remote attackers to trick users into granting an HTTPS-Only exception for insecure HTTP content. The warning's exception control becomes actionable without an activation delay, so a timed page transition can place it beneath an expected game control. Exploitation requires opt-in HTTPS-Only mode, user interaction, and a network vantage point or trusted HTTP service; the bounded result is loading insecure HTTP content.

CVSS severity6.5
Medium
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Clickjacking in Mozilla Firefox before 120 allows remote attackers to trick users into granting an HTTPS-Only exception for insecure HTTP content. The warning's exception control becomes actionable without an activation delay, so a timed page transition can place it beneath an expected game control. Exploitation requires opt-in HTTPS-Only mode, user interaction, and a network vantage point or trusted HTTP service; the bounded result is loading insecure HTTP content.

The record

CVE
CVE-2023-6211
Published
Nov 21, 2023
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-1021, T1204
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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 <120

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <120

Published CVSS scores

6.5NVDCVSS: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-1021Improper Restriction of Rendered UI Layers or Frames
T1204User Execution

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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