CVE-2025-49710: An integer overflow was present in `OrderedHashTable` used by the JavaScript engine

Q: How do I fix CVE-2025-49710?

firefox: upgrade to 139.0.4. Exact commands for each OS are on this page.

Q: Is CVE-2025-49710 being exploited?

CVE-2025-49710 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-2025-49710 affect?

CVE-2025-49710 affects firefox. Severity is critical (CVSS 9.8). An integer overflow was present in `OrderedHashTable` used by the JavaScript engine. This vulnerability was fixed in Firefox 139.0.4.

Q: How urgent is CVE-2025-49710?

Priority 56/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2025-49710 is a critical-severity flaw (CVSS 9.8) affecting firefox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An integer overflow was present in `OrderedHashTable` used by the JavaScript engine. This vulnerability was fixed in Firefox 139.0.4.

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-190
Published	2025-06-11
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

2025-06-11 12:15 UTCPublished CVE record published
2026-10-23 22:10 UTCUpdated Record last modified

mozilla firefox UPGRADE

Affected: < 139.0.4

Fixed in: 139.0.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 139.0.4 (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.

Exact fixes by distribution

Fedora 46 · pspp · FIXED · 2.1.3-2.fc46 · FEDORA-2026-0d6444911b · source

sudo dnf upgrade --advisory=FEDORA-2026-0d6444911b

Fedora ELN · barman · FIXED · 3.20.1-3.eln159 · FEDORA-2026-45ecf042c2 · source

sudo dnf upgrade --advisory=FEDORA-2026-45ecf042c2

Ubuntu 22.04 · firefox · NOT AFFECTED

Ubuntu 24.04 · firefox · NOT AFFECTED

Ubuntu 24.10 · firefox · NOT AFFECTED

Ubuntu 25.04 · firefox · NOT AFFECTED

Ubuntu 25.10 · firefox · NOT AFFECTED

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-2025-49710?

firefox: upgrade to 139.0.4. Exact commands for each OS are on this page.

Is CVE-2025-49710 being exploited?

CVE-2025-49710 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-2025-49710 affect?

CVE-2025-49710 affects firefox. Severity is critical (CVSS 9.8). An integer overflow was present in `OrderedHashTable` used by the JavaScript engine. This vulnerability was fixed in Firefox 139.0.4.

How urgent is CVE-2025-49710?

Priority 56/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

Mozilla Firefox vulnerabilities

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References

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