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CVE-2018-5116

30
FAUCET Score

CVE-2018-5116 is a critical vulnerability affecting Firefox versions prior to 58, where WebExtensions with the "ActiveTab" permission could bypass the same-origin policy. This allowed malicious extensions to inject and interact with cross-origin frames within the active tab, circumventing user expectations. With a CVSS score of 9.8, it poses a high risk of complete compromise (confidentiality, integrity, availability) due to its network-based, low-complexity attack vector requiring no user interaction. Despite its severity, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 57.0.4CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
14.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
17.10CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*
< 58CPE match
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.18%
Probability of exploitation in next 30 days
EPSS Percentile
64.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0118 is in the 50th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

mozillavendor investigatingvia nvd_reference
View patch

References

bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions Required
usn.ubuntu.com / 3544-1
Third Party Advisory
mozilla.org / security/advisories/mfsa2018-02
Vendor Advisory
securityfocus.com / bid/102786
Third Party AdvisoryVDB Entry
securitytracker.com / id/1040270
Third Party AdvisoryVDB Entry