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CVE-2018-5135

23
FAUCET Score

CVE-2018-5135 describes a vulnerability in Firefox versions prior to 59 where WebExtensions could bypass security restrictions. This allowed them to inject scripts into unauthorized contexts, including other WebExtensions or unprivileged "about:" pages. Rated High (CVSS 7.5), the vulnerability has a network attack vector and high integrity impact, but no confidentiality or availability impact. There is no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 59.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 59CPE match
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.55%
Probability of exploitation in next 30 days
EPSS Percentile
72.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0155 is in the 54th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 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

References

bugzilla.mozilla.org / show_bug.cgi
Permissions Required
usn.ubuntu.com / 3596-1
Third Party Advisory
mozilla.org / security/advisories/mfsa2018-06
Vendor Advisory
securityfocus.com / bid/103386
Third Party AdvisoryVDB Entry
securitytracker.com / id/1040514
Third Party AdvisoryVDB Entry