CVE-2025-54143 Sandboxed iframes could allow local downloads despite sandbox restrictions

What is CVE-2025-54143?

CVE-2025-54143 is a critical vulnerability in Mozilla Firefox, published on 19 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Sandboxed iframes on webpages could potentially allow downloads to the device, bypassing the expected sandbox restrictions declared on the parent page. This vulnerability was fixed in Firefox for iOS 141.

Weakness: CWE-693

Which versions are affected by CVE-2025-54143?

It affects 1 product.

Products include Mozilla Firefox.

How do I fix CVE-2025-54143?

No fix has been published for CVE-2025-54143 yet. Limit exposure of the affected software until one is available.

Is CVE-2025-54143 being exploited?

There is no known exploitation of CVE-2025-54143 in the wild and no public exploit code.

Other vulnerabilities in Mozilla Firefox

• CVE-2019-11708 Mozilla Firefox and Thunderbird Sandbox Escape Exploited Critical 10.0
• CVE-2010-3765 Mozilla Multiple Products Remote Code Execution Exploited Critical 9.8
• CVE-2022-26486 Mozilla Firefox Use-After-Free Exploited Critical 9.6
• CVE-2022-26485 Mozilla Firefox Use-After-Free Exploited High 8.8
• CVE-2019-11707 Mozilla Firefox and Thunderbird Type Confusion Exploited High 8.8

All Mozilla Firefox vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-x7hr-j7rg-h68w.