CVE-2026-13356: A malicious webpage could interrupt a pending navigation by enqueuing a synchronous JavaScript dialog, causing

Q: How do I fix CVE-2026-13356?

firefox: upgrade to 152.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-13356 being exploited?

CVE-2026-13356 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-2026-13356 affect?

CVE-2026-13356 affects firefox. Severity is medium (CVSS 6.3). A malicious webpage could interrupt a pending navigation by enqueuing a synchronous JavaScript dialog, causing the browser UI to display the destination origin in the address bar while continuing to render attacker-controlled content. This

Q: How urgent is CVE-2026-13356?

Priority 25/100. No elevated risk signals yet.

Routine

MEDIUM 6.3UPGRADE

CVE-2026-13356 is a medium-severity flaw (CVSS 6.3) affecting firefox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A malicious webpage could interrupt a pending navigation by enqueuing a synchronous JavaScript dialog, causing the browser UI to display the destination origin in the address bar while continuing to render attacker-controlled content. This vulnerability was fixed in Firefox for iOS 152.3.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 88%)
CISA exploited list	No
Weakness	CWE-451
Published	2026-07-07
Last modified	2026-10-25

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-07 00:16 UTCPublished CVE record published
2026-10-25 20:10 UTCUpdated Record last modified

mozilla firefox UPGRADE

Affected: < 152.3

Fixed in: 152.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 152.3 (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.

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-2026-13356?

firefox: upgrade to 152.3. Exact commands for each OS are on this page.

Is CVE-2026-13356 being exploited?

CVE-2026-13356 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-2026-13356 affect?

CVE-2026-13356 affects firefox. Severity is medium (CVSS 6.3). A malicious webpage could interrupt a pending navigation by enqueuing a synchronous JavaScript dialog, causing the browser UI to display the destination origin in the address bar while continuing to render attacker-controlled content. This

How urgent is CVE-2026-13356?

Priority 25/100. No elevated risk signals yet.

Software pages

iOS vulnerabilities · Mozilla Firefox vulnerabilities

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References

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