CVE-2017-7803 Security feature bypass in Firefox

What is CVE-2017-7803?

CVE-2017-7803 is a high-severity vulnerability in Debian Debian Linux, published on 11 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

When a page's content security policy (CSP) header contains a "sandbox" directive, other directives are ignored. This results in the incorrect enforcement of CSP. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

Weakness: CWE-269

Which versions are affected by CVE-2017-7803?

It affects 8 products.

Products include Debian Debian Linux, Mozilla Firefox, Mozilla Thunderbird, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux Server, Redhat Enterprise Linux Server Aus and 2 more.

How do I fix CVE-2017-7803?

Upgrade to a fixed version.

Is CVE-2017-7803 being exploited?

There is no known exploitation of CVE-2017-7803 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2017-7803, GHSA-6465-6pfq-mj4h, UBUNTU-CVE-2017-7803.