CVE-2015-4490

What it is

The nsCSPHostSrc::permits function in dom/security/nsCSPUtils.cpp in Mozilla Firefox before 40.0 does not implement the Content Security Policy Level 2 exceptions for the blob, data, and filesystem URL schemes during wildcard source-expression matching, which might make it easier for remote attackers to conduct cross-site scripting (XSS) attacks by leveraging unexpected policy-enforcement behavior.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

2.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2015-08-16 01:59 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 00:27 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.4% in the next 30 days (EPSS).
• Severity: 4.3 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2015-08-16 01:59 UTC

Last modified

2026-06-17 00:27 UTC

Exploit probability

2.4% · EPSS, next 30 days

Weakness

CWE-79 · Cross-site scripting

Record status

Modified

Affected

• Mozilla Firefox ≤ 39.0.3
• Canonical Ubuntu Linux 12.04
• Canonical Ubuntu Linux 14.04
• Canonical Ubuntu Linux 15.04
• Opensuse 13.1
• Opensuse 13.2
• Oracle Solaris 11.3

Attack profile CVSS 2.0 · 4.3

Attack vector

Network

Complexity

Medium

Authentication

None

Confidentiality

None

Integrity

Partial

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2015-4490.md and follow it. Check whether this project is affected by CVE-2015-4490. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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