#VU9321 CSP policy bypass in Mozilla Firefox - CVE-2017-7834

Vulnerability identifier: #VU9321

Vulnerability risk: Low

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2017-7834

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to bypass certain security restrictions.

A data: URL loaded in a new tab did not inherit the Content Security Policy (CSP) of the original page, allowing for bypasses of the policy including the execution of JavaScript. In prior versions when data: documents also inherited the context of the original page this would allow for potential cross-site scripting (XSS) attacks.

Mitigation
Update to version Firefox 57.

Vulnerable software versions

Mozilla Firefox: 53.0 - 56.0.1

---

External links
https://www.mozilla.org/en-US/security/advisories/mfsa2017-24/

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.