CVE-2017-7839 Cross-site scripting in Firefox

What is CVE-2017-7839?

CVE-2017-7839 is a medium-severity cross-site scripting vulnerability in Mozilla Firefox, published on 11 Jun 2018. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Control characters prepended before "javascript:" URLs pasted in the addressbar can cause the leading characters to be ignored and the pasted JavaScript to be executed instead of being blocked. This could be used in social engineering and self-cross-site-scripting (self-XSS) attacks where users are convinced to copy and paste text into the addressbar. This vulnerability affects Firefox < 57.

Weakness: CWE-79

Which versions are affected by CVE-2017-7839?

It affects 1 product.

Products include Mozilla Firefox.

How do I fix CVE-2017-7839?

Upgrade to a fixed version.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2017-7839 being exploited?

There is no known exploitation of CVE-2017-7839 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-42vq-2prv-qxmf, UBUNTU-CVE-2017-7839.