CVE-2023-25732: When encoding data from an <code>inputStream</code> in <code>xpcom</code> the size of the input being encoded

Q: How do I fix CVE-2023-25732?

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-2023-25732 being exploited?

CVE-2023-25732 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-2023-25732 affect?

CVE-2023-25732 affects firefox, firefox esr, thunderbird. Severity is high (CVSS 8.8). When encoding data from an inputStream in xpcom the size of the input being encoded was not correctly calculated potentially leading to an out of bounds memory write. This vulnerability affects Firefox < 110, Thund

Q: How urgent is CVE-2023-25732?

Priority 47/100. High severity; CISA SSVC: public proof of concept

This month

HIGH 8.8UPGRADEUPGRADEUPGRADE

CVE-2023-25732 is a high-severity flaw (CVSS 8.8) affecting firefox, firefox esr, thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

When encoding data from an <code>inputStream</code> in <code>xpcom</code> the size of the input being encoded was not correctly calculated potentially leading to an out of bounds memory write. This vulnerability affects Firefox < 110, Thunderbird < 102.8, and Firefox ESR < 102.8.

Why this priority

High severity
CISA SSVC: public proof of concept

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-787
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

Ubuntu 20.04 · firefox · FIXED · 110.0+build3-0ubuntu0.20.04.1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "110.0+build3-0ubuntu0.20.04.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · firefox · NOT AFFECTED

Ubuntu 20.04 · thunderbird · FIXED · 1:102.8.0+build2-0ubuntu0.20.04.1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:102.8.0+build2-0ubuntu0.20.04.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · thunderbird · FIXED · 1:102.8.0+build2-0ubuntu0.22.04.1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:102.8.0+build2-0ubuntu0.22.04.1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · firefox-esr · FIXED · 102.8.0esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "102.8.0esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 102.8.0esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "102.8.0esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · thunderbird · FIXED · 1:102.8.0-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:102.8.0-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · thunderbird · FIXED · 1:102.8.0-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:102.8.0-1" && echo PATCHED || echo STILL-VULNERABLE

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

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=1804564

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-2023-25732?

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-2023-25732 being exploited?

CVE-2023-25732 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-2023-25732 affect?

CVE-2023-25732 affects firefox, firefox esr, thunderbird. Severity is high (CVSS 8.8). When encoding data from an <code>inputStream</code> in <code>xpcom</code> the size of the input being encoded was not correctly calculated potentially leading to an out of bounds memory write. This vulnerability affects Firefox < 110, Thund

How urgent is CVE-2023-25732?

Priority 47/100. High severity; CISA SSVC: public proof of concept

Software pages

Mozilla Firefox vulnerabilities

Related CVEs

CVE-2023-29531 CRITICAL 9.8 UPGRADE UPGRADE An attacker could have caused an out of bounds memory access using WebGL APIs, leading to memory corruption an
CVE-2023-34416 CRITICAL 9.8 UPGRADE UPGRADE Memory safety bugs present in Firefox 113, Firefox ESR 102.11, and Thunderbird 102.12
CVE-2026-5731 CRITICAL 9.8 DOWNGRADE DOWNGRADE Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.
CVE-2023-37202 HIGH 8.8 UPGRADE UPGRADE Cross-compartment wrappers wrapping a scripted proxy could have caused objects from other compartments to be s
CVE-2023-37211 HIGH 8.8 UPGRADE UPGRADE Memory safety bugs present in Firefox 114, Firefox ESR 102.12, and Thunderbird 102.12

References

← Back to latest CVEs