CVE-2023-6870Public exploitNetwork attack vector

Page spoofing via starved fullscreen Toast queue

Published Dec 19, 2023 · Updated Feb 13, 2025

UI spoofing in Mozilla Firefox for Android before 121 allows context-dependent attackers to hide fullscreen-entry notifications. Firefox used an Android Toast for the fullscreen-entry warning; a background app could starve the shared Toast queue with repeated messages. A user had to install the interfering app and enter fullscreen content, after which hidden browser chrome enabled page-origin spoofing.

CVSS severity4.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

UI spoofing in Mozilla Firefox for Android before 121 allows context-dependent attackers to hide fullscreen-entry notifications. Firefox used an Android Toast for the fullscreen-entry warning; a background app could starve the shared Toast queue with repeated messages. A user had to install the interfering app and enter fullscreen content, after which hidden browser chrome enabled page-origin spoofing.

The record

CVE
CVE-2023-6870
Published
Dec 19, 2023
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 19, 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 <121

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <121

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/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

No sourced classifications are available.

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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