CVE-2023-28163: When downloading files through the Save As dialog on Windows with suggested filenames containing environment v

Q: How do I fix CVE-2023-28163?

firefox: upgrade to 111.0; firefox esr: upgrade to 102.9; thunderbird: upgrade to 102.9. Exact commands for each OS are on this page.

Q: Is CVE-2023-28163 being exploited?

CVE-2023-28163 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-2023-28163 affect?

CVE-2023-28163 affects firefox, firefox esr, thunderbird. Severity is medium (CVSS 6.5). When downloading files through the Save As dialog on Windows with suggested filenames containing environment variable names, Windows would have resolved those in the context of the current user. *This bug only affects Firefox on Windows

This month

MEDIUM 6.5UPGRADEUPGRADEUPGRADE

CVE-2023-28163 is a medium-severity flaw (CVSS 6.5) affecting firefox, firefox esr, thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

When downloading files through the Save As dialog on Windows with suggested filenames containing environment variable names, Windows would have resolved those in the context of the current user. <br>*This bug only affects Firefox on Windows. Other versions of Firefox are unaffected.*. This vulnerability affects Firefox < 111, Firefox ESR < 102.9, and Thunderbird < 102.9.

Why this priority

CISA SSVC: public proof of concept

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 44%)
CISA exploited list	No
Weakness	CWE-22
Published	2023-06-02
Last modified	2026-10-23

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-10-23 · 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
2026-10-23 23:10 UTCUpdated Record last modified

mozilla firefox UPGRADE

Affected: < 111.0

Fixed in: 111.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 111.0 (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: < 102.9

Fixed in: 102.9

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 102.9 (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: < 102.9

Fixed in: 102.9

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 102.9 (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 · sugar-toolkit-gtk3 · FIXED · 0.122-2.fc46 · FEDORA-2026-d11eb2faf0 · source

sudo dnf upgrade --advisory=FEDORA-2026-d11eb2faf0

Fedora ELN · ntpd-rs · FIXED · 1.7.2-3.eln159 · FEDORA-2026-57e4a99310 · source

sudo dnf upgrade --advisory=FEDORA-2026-57e4a99310

Ubuntu 22.04 · firefox · NOT AFFECTED

Ubuntu 22.04 · thunderbird · 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-102.9.0-r0

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

Alpine 3.21 · firefox-esr · FIXED · firefox-esr-102.9.0-r0

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

Alpine 3.22 · firefox-esr · FIXED · firefox-esr-102.9.0-r0

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

Alpine 3.23 · firefox-esr · FIXED · firefox-esr-102.9.0-r0

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

Amazon Linux 2 · see advisory · FIXED · ALAS2-2023-1988 · source

sudo yum update --advisory=ALAS2-2023-1988

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=1817768

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-2023-28163?

firefox: upgrade to 111.0; firefox esr: upgrade to 102.9; thunderbird: upgrade to 102.9. Exact commands for each OS are on this page.

Is CVE-2023-28163 being exploited?

CVE-2023-28163 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-2023-28163 affect?

CVE-2023-28163 affects firefox, firefox esr, thunderbird. Severity is medium (CVSS 6.5). When downloading files through the Save As dialog on Windows with suggested filenames containing environment variable names, Windows would have resolved those in the context of the current user. <br>*This bug only affects Firefox on Windows

How urgent is CVE-2023-28163?

Priority 40/100. CISA SSVC: public proof of concept

Software pages

Windows vulnerabilities · Mozilla Firefox vulnerabilities

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References

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