Mozilla Firefox up to 147.3 on iOS Web Contents clickjacking

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 147.3 on iOS. It has been rated as problematic. This impacts an unknown function of the component Web Contents Handler. The manipulation leads to clickjacking. This vulnerability is listed as CVE-2026-2634. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 147.3 on iOS. It has been rated as problematic. This issue affects an unknown function of the component Web Contents Handler. The manipulation with an unknown input leads to a clickjacking vulnerability. Using CWE to declare the problem leads to CWE-451. The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks. Impacted is integrity. The summary by CVE is:

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 affects Firefox for iOS < 147.4.

It is possible to read the advisory at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2026-2634 since 02/17/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 03/04/2026). The attack technique deployed by this issue is T1566.003 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 300439 (Linux Distros Unpatched Vulnerability : CVE-2026-2634), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 147.4 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (300439) and CERT Bund (WID-SEC-2026-0497). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Debian Linux
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• IGEL OS
• SUSE openSUSE
• RESF Rocky Linux
• Mozilla Firefox
• Mozilla Firefox ESR
• Mozilla Thunderbird

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 147.0
• 147.1
• 147.2
• 147.3

License

• open-source

Website

• Vendor: https://www.mozilla.org/
• Product: https://www.mozilla.org/en-US/firefox/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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