CVE-2019-9803 Security feature bypass in Firefox

What is CVE-2019-9803?

CVE-2019-9803 is a high-severity vulnerability in Mozilla Firefox, published on 26 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The Upgrade-Insecure-Requests (UIR) specification states that if UIR is enabled through Content Security Policy (CSP), navigation to a same-origin URL must be upgraded to HTTPS. Firefox will incorrectly navigate to an HTTP URL rather than perform the security upgrade requested by the CSP in some circumstances, allowing for potential man-in-the-middle attacks on the linked resources. This vulnerability affects Firefox < 66.

Weakness: CWE-346

Which versions are affected by CVE-2019-9803?

It affects 1 product.

Products include Mozilla Firefox.

How do I fix CVE-2019-9803?

Upgrade to a fixed version.

Is CVE-2019-9803 being exploited?

There is no known exploitation of CVE-2019-9803 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-6h7p-w66v-f7vw, UBUNTU-CVE-2019-9803.