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CVE-2024-4367: A type check was missing when handling fonts in PDF.js, which would allow arbitrary JavaScript execution in th

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HIGH 8.8WATCHLISTUPGRADEUPGRADEMITIGATE

CVE-2024-4367 is a high-severity flaw (CVSS 8.8) affecting firefox, thunderbird, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A type check was missing when handling fonts in PDF.js, which would allow arbitrary JavaScript execution in the PDF.js context. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.

Why this priority

  • High severity
  • EPSS top 1%: very likely to be exploited
  • Public exploit reference
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score8.8 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionRequired
EPSS exploit chance70.7% (top 1%)
CISA exploited listNo
WeaknessCWE-754
Published2024-05-14
Last modified2026-06-17
Publisher (CNA): Mozilla Corporation · Vendor: debian · mozilla · open-xchange

Share: LinkedIn · X · Reddit

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

mozilla firefox UPGRADE
Affected: < 115.11.0 · < 126.0
Fixed in: 115.11.0, 126.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy firefox || rpm -q firefox || firefox --version
2. UPGRADE to 115.11.0 (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 thunderbird UPGRADE
Affected: < 115.11.0
Fixed in: 115.11.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version
2. UPGRADE to 115.11.0 (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.
debian debian linux MITIGATE
Affected: 10.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 10.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
open-xchange open-xchange appsuite frontend UPGRADE
Affected: < 7.10.6 · 7.10.6 · 7.10.6 revision10 · 7.10.6 revision11 · 7.10.6 revision12 · 7.10.6 revision13 · 7.10.6 revision14 · 7.10.6 revision15
Fixed in: 7.10.6
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy open-xchange-appsuite-frontend || rpm -q open-xchange-appsuite-frontend || open-xchange-appsuite-frontend --version
2. UPGRADE to 7.10.6 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade open-xchange-appsuite-frontend
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade open-xchange-appsuite-frontend
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
npm · pdfjs-dist · FIXED · 4.2.67 · vulnerable: <= 4.1.392 · source
npm install pdfjs-dist@">=4.2.67" npm ls pdfjs-dist
Fedora 46 · noctalia · FIXED · 5.4.1-1.fc46 · FEDORA-2026-a4755e8ef7 · source
sudo dnf upgrade --advisory=FEDORA-2026-a4755e8ef7
Fedora ELN · efifs · FIXED · 1.13-1.eln159 · FEDORA-2026-3fd0bb7307 · source
sudo dnf upgrade --advisory=FEDORA-2026-3fd0bb7307
Ubuntu 22.04 · firefox · NOT AFFECTED
Ubuntu 24.04 · firefox · NOT AFFECTED
Ubuntu 20.04 · firefox · FIXED · 126.0+build2-0ubuntu0.20.04.1
sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "126.0+build2-0ubuntu0.20.04.1" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 24.04 · thunderbird · NOT AFFECTED
Ubuntu 20.04 · thunderbird · FIXED · 1:115.11.0+build2-0ubuntu0.20.04.1
sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:115.11.0+build2-0ubuntu0.20.04.1" && echo PATCHED || echo STILL-VULNERABLE
Debian 12 · firefox-esr · FIXED · 115.11.0esr-1~deb12u1
sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "115.11.0esr-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · firefox-esr · FIXED · 115.11.0esr-1
sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "115.11.0esr-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 12 · thunderbird · FIXED · 1:115.11.0-1~deb12u1
sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:115.11.0-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · thunderbird · FIXED · 1:115.11.0-1
sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:115.11.0-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 7 · firefox · FIXED · firefox-115.11.0-1.el7_9
sudo dnf upgrade --advisory=RHSA-2024:2881 rpm -q firefox
RHEL 7 · thunderbird · FIXED · thunderbird-115.11.0-1.el7_9
sudo dnf upgrade --advisory=RHSA-2024:2913 rpm -q thunderbird
RHEL 7 Extended Lifecycle Support · webkitgtk4 · FIXED · webkitgtk4-2.52.5-1.el7_9
sudo dnf upgrade --advisory=RHSA-2026:58564 rpm -q webkitgtk4
RHEL 8 · firefox · FIXED · firefox-115.11.0-1.el8_10
sudo dnf upgrade --advisory=RHSA-2024:3783 rpm -q firefox
RHEL 8 · thunderbird · FIXED · thunderbird-115.11.0-1.el8_10
sudo dnf upgrade --advisory=RHSA-2024:3784 rpm -q thunderbird
Amazon Linux 2 · see advisory · FIXED · ALAS2-2024-2561 · source
sudo yum update --advisory=ALAS2-2024-2561

Public exploits and detection

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

Advisories and coverage

Official advisories

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-2024-4367?

firefox: upgrade to 115.11.0, 126.0; thunderbird: upgrade to 115.11.0; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2024-4367 being exploited?

CVE-2024-4367 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-2024-4367 affect?

CVE-2024-4367 affects firefox, thunderbird, debian linux. Severity is high (CVSS 8.8). A type check was missing when handling fonts in PDF.js, which would allow arbitrary JavaScript execution in the PDF.js context. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.

How urgent is CVE-2024-4367?

Priority 66/100. High severity; EPSS top 1%: very likely to be exploited; Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities · Mozilla Firefox vulnerabilities · Mozilla Thunderbird vulnerabilities

Related CVEs

References

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