CVE-2023-25730: A background script invoking <code>requestFullscreen</code> and then blocking the main thread could force the

Q: How do I fix CVE-2023-25730?

firefox: upgrade to 110.0; firefox esr: upgrade to 102.8; thunderbird: upgrade to 102.8. Exact commands for each OS are on this page.

Q: Is CVE-2023-25730 being exploited?

CVE-2023-25730 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-2023-25730 affect?

CVE-2023-25730 affects firefox, firefox esr, thunderbird. Severity is medium (CVSS 5.4). A background script invoking requestFullscreen and then blocking the main thread could force the browser into fullscreen mode indefinitely, resulting in potential user confusion or spoofing attacks. This vulnerability affects F

Routine

MEDIUM 5.4UPGRADEUPGRADEUPGRADE

CVE-2023-25730 is a medium-severity flaw (CVSS 5.4) affecting firefox, firefox esr, thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A background script invoking <code>requestFullscreen</code> and then blocking the main thread could force the browser into fullscreen mode indefinitely, resulting in potential user confusion or spoofing attacks. This vulnerability affects Firefox < 110, Thunderbird < 102.8, and Firefox ESR < 102.8.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-1021
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 UPGRADE

Affected: < 110.0

Fixed in: 110.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 110.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firefox

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

mozilla firefox esr UPGRADE

Affected: < 102.8

Fixed in: 102.8

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 102.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firefox-esr

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox-esr

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

mozilla thunderbird UPGRADE

Affected: < 102.8

Fixed in: 102.8

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version

2. UPGRADE to 102.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade thunderbird

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade thunderbird

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2023-25730?

firefox: upgrade to 110.0; firefox esr: upgrade to 102.8; thunderbird: upgrade to 102.8. Exact commands for each OS are on this page.

Is CVE-2023-25730 being exploited?

CVE-2023-25730 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-2023-25730 affect?

CVE-2023-25730 affects firefox, firefox esr, thunderbird. Severity is medium (CVSS 5.4). A background script invoking <code>requestFullscreen</code> and then blocking the main thread could force the browser into fullscreen mode indefinitely, resulting in potential user confusion or spoofing attacks. This vulnerability affects F

How urgent is CVE-2023-25730?

Priority 30/100. No elevated risk signals yet.

Software pages

Mozilla Firefox vulnerabilities

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References

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