CVE-2023-25743: A lack of in app notification for entering fullscreen mode could have lead to a malicious website spoofing bro

Q: How do I fix CVE-2023-25743?

firefox focus: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2023-25743 being exploited?

CVE-2023-25743 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2023-25743 affect?

CVE-2023-25743 affects firefox focus. Severity is high (CVSS 7.5). A lack of in app notification for entering fullscreen mode could have lead to a malicious website spoofing browser chrome. *This bug only affects Firefox Focus. Other versions of Firefox are unaffected.*. This vulnerability affects Firef

This month

HIGH 7.5REMOTEMITIGATE

CVE-2023-25743 is a high-severity flaw (CVSS 7.5) affecting firefox focus. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A lack of in app notification for entering fullscreen mode could have lead to a malicious website spoofing browser chrome.<br>*This bug only affects Firefox Focus. Other versions of Firefox are unaffected.*. This vulnerability affects Firefox < 110 and Firefox ESR < 102.8.

Why this priority

High severity
CISA SSVC: public proof of concept
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 49%)
CISA exploited list	No
Weakness	CWE-290
Published	2023-06-02
Last modified	2026-10-24

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-06-02 17:15 UTCPublished CVE record published
2026-10-24 13:10 UTCUpdated Record last modified

mozilla firefox focus MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy firefox-focus || rpm -q firefox-focus || firefox-focus --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · gnome-shell-extension-tiling-assistant · FIXED · 56-1.fc46 · FEDORA-2026-ebf66a5321 · source

sudo dnf upgrade --advisory=FEDORA-2026-ebf66a5321

Ubuntu 22.04 · firefox · NOT AFFECTED

Debian 12 · firefox-esr · NOT AFFECTED

Debian 13 · firefox-esr · NOT AFFECTED

RHEL 7 · firefox · FIXED · firefox-102.8.0-2.el7_9

sudo dnf upgrade --advisory=RHSA-2023:0812 rpm -q firefox

RHEL 7 · thunderbird · FIXED · thunderbird-102.8.0-2.el7_9

sudo dnf upgrade --advisory=RHSA-2023:0817 rpm -q thunderbird

RHEL 8 · firefox · FIXED · firefox-102.8.0-2.el8_7

sudo dnf upgrade --advisory=RHSA-2023:0808 rpm -q firefox

RHEL 8 · thunderbird · FIXED · thunderbird-102.8.0-2.el8_7

sudo dnf upgrade --advisory=RHSA-2023:0821 rpm -q thunderbird

RHEL 8.1 Update Services for SAP Solutions · firefox · FIXED · firefox-102.8.0-2.el8_1

sudo dnf upgrade --advisory=RHSA-2023:0806 rpm -q firefox

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: bugzilla.mozilla.org/show_bug.cgi?id=1800203

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-25743?

firefox focus: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-25743 being exploited?

CVE-2023-25743 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-25743 affect?

CVE-2023-25743 affects firefox focus. Severity is high (CVSS 7.5). A lack of in app notification for entering fullscreen mode could have lead to a malicious website spoofing browser chrome.<br>*This bug only affects Firefox Focus. Other versions of Firefox are unaffected.*. This vulnerability affects Firef

How urgent is CVE-2023-25743?

Priority 47/100. High severity; CISA SSVC: public proof of concept; Remotely exploitable, no login, no user action

Software pages

Google Chrome vulnerabilities · Mozilla Firefox vulnerabilities

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References

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