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CVE-2015-4516

24
FAUCET Score

CVE-2015-4516 describes a critical vulnerability in Mozilla Firefox versions prior to 41.0, allowing remote attackers to bypass ECMAScript 5 (ES5) API protection mechanisms. By crafting a malicious web page that avoids ES5 APIs, an attacker could modify immutable properties and execute arbitrary JavaScript code with chrome privileges. This vulnerability carries a CVSS score of 9.3, indicating a high severity with network-based attacks, medium complexity, and complete compromise of confidentiality, integrity, and availability. While no active exploitation, public exploit code, or significant community discussion has been observed, its high FAUCET Risk Score of 75/100 highlights its potential impact.

Impacted Technologies

VendorProductVersion(s)CPE
<= 40.0.3CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

9.3HIGH

AV:N/AC:M/Au:N/C:C/I:C/A:C

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
8.6
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
3.46%
Probability of exploitation in next 30 days
EPSS Percentile
87.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0346 is in the 47th percentile among its peer group of 8,915 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2015-4516Important

Mozilla: JavaScript immutable property enforcement can be bypassed (MFSA 2015-109)

Sep 22, 2015

References

lists.opensuse.org / opensuse-security-announce/2015-10/msg00000.html
lists.opensuse.org / opensuse-security-announce/2015-10/msg00005.html
bugzilla.mozilla.org / show_bug.cgi
mozilla.org / security/announce/2015/mfsa2015-109.html
Vendor Advisory
oracle.com / technetwork/topics/security/bulletinapr2016-2952098.html
securityfocus.com / bid/76815
securitytracker.com / id/1033640
ubuntu.com / usn/USN-2743-1
ubuntu.com / usn/USN-2743-2
ubuntu.com / usn/USN-2743-3
ubuntu.com / usn/USN-2743-4