CVE-2023-25734: After downloading a Windows <code>.url</code> shortcut from the local filesystem, an attacker could supply a r

Q: How do I fix CVE-2023-25734?

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-2023-25734 being exploited?

CVE-2023-25734 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-2023-25734 affect?

CVE-2023-25734 affects firefox, firefox esr, thunderbird. Severity is high (CVSS 8.1). After downloading a Windows .url shortcut from the local filesystem, an attacker could supply a remote path that would lead to unexpected network requests from the operating system. This also had the potential to leak NTLM cred

This month

HIGH 8.1UPGRADEUPGRADEUPGRADE

CVE-2023-25734 is a high-severity flaw (CVSS 8.1) affecting firefox, firefox esr, thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

After downloading a Windows <code>.url</code> shortcut from the local filesystem, an attacker could supply a remote path that would lead to unexpected network requests from the operating system. This also had the potential to leak NTLM credentials to the resource.<br>*This bug only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox < 110, Thunderbird < 102.8, and Firefox ESR < 102.8.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-601
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.

Exact fixes by distribution

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

Debian 12 · thunderbird · NOT AFFECTED

Debian 13 · thunderbird · NOT AFFECTED

RHEL 6 · firefox · NOT AFFECTED

RHEL 6 · thunderbird · NOT AFFECTED

RHEL 7 · firefox · NOT AFFECTED

RHEL 7 · thunderbird · NOT AFFECTED

RHEL 8 · firefox · NOT AFFECTED

Alpine 3.20 · firefox-esr · FIXED · firefox-esr-102.8.0-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.21 · firefox-esr · FIXED · firefox-esr-102.8.0-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.22 · firefox-esr · FIXED · firefox-esr-102.8.0-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.23 · firefox-esr · FIXED · firefox-esr-102.8.0-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Amazon Linux 2 · see advisory · FIXED · ALAS2-2023-1983 · source

sudo yum update --advisory=ALAS2-2023-1983

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=1809923
Write-up: bugzilla.mozilla.org/show_bug.cgi?id=1810143

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-2023-25734?

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-2023-25734 being exploited?

CVE-2023-25734 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-2023-25734 affect?

CVE-2023-25734 affects firefox, firefox esr, thunderbird. Severity is high (CVSS 8.1). After downloading a Windows <code>.url</code> shortcut from the local filesystem, an attacker could supply a remote path that would lead to unexpected network requests from the operating system. This also had the potential to leak NTLM cred

How urgent is CVE-2023-25734?

Priority 47/100. High severity; Public exploit reference

Software pages

Windows vulnerabilities · Mozilla Firefox vulnerabilities

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References

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