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CVE-2018-12399

18
FAUCET Score

CVE-2018-12399 is a medium-severity vulnerability affecting Firefox versions prior to 63, where a malicious title argument during protocol handler registration could mislead users into approving unintended handlers. This user interface vulnerability has a low impact, potentially leading to information disclosure (CVSS 4.3). There is no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 63.0CPE 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:*:*:*
18.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
18.10CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.36%
Probability of exploitation in next 30 days
EPSS Percentile
68.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0136 is in the 81st percentile among its peer group of 26,234 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 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 (4)

mozillavendor investigatingvia nvd_reference
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox

Vendor Advisories (1)

redhatCVE-2018-12399Low

firefox: Spoofing of protocol registration notification bar

Oct 23, 2018

References

bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions RequiredVendor Advisory
usn.ubuntu.com / 3801-1
Third Party Advisory
mozilla.org / security/advisories/mfsa2018-26
Vendor Advisory
securityfocus.com / bid/105721
Third Party AdvisoryVDB Entry
securitytracker.com / id/1041944
Third Party AdvisoryVDB Entry