How severe is CVE-2026-2634?

CVE-2026-2634 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-2634 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-2634?

CVE-2026-2634 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-2634?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-2634 have an EU (EUVD) identifier?

Yes. CVE-2026-2634 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8446.

When was CVE-2026-2634 published?

CVE-2026-2634 was published on 2026-02-24 and last updated on 2026-06-17.

CVE-2026-2634

CVE-2026-2634 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-451.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8446
Weakness: CWE-451
Affected product: Mozilla Firefox
Published: 2026-02-24
Last modified: 2026-06-17

Description

Malicious scripts could cause desynchronization between the address bar and web content before a response is received in Firefox iOS, allowing attacker-controlled pages to be presented under spoofed domains. This vulnerability was fixed in Firefox for iOS 147.4.

Frequently asked questions

What is CVE-2026-2634?: Malicious scripts could cause desynchronization between the address bar and web content before a response is received in Firefox iOS, allowing attacker-controlled pages to be presented under spoofed domains. This vulnerability was fixed in Firefox for iOS 147.4.
How severe is CVE-2026-2634?: CVE-2026-2634 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-2634 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-2634?: CVE-2026-2634 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-2634?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-2634 have an EU (EUVD) identifier?: Yes. CVE-2026-2634 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8446.
When was CVE-2026-2634 published?: CVE-2026-2634 was published on 2026-02-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:iphone_os:*:*

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