Public proof of conceptFix available

CVE-2018-4121

Q: Is CVE-2018-4121 actively exploited?

Active exploitation of CVE-2018-4121 has not been confirmed. Its EPSS score was 13.1% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2018-4121?

CVE-2018-4121 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

A public proof of concept exists; no exploitation attested.

Published2018-04-03
Fixed in7.4
WeaknessCWE-119

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An issue was discovered in certain Apple products. iOS before 11.3 is affected. Safari before 11.1 is affected. iCloud before 7.4 on Windows is affected. iTunes before 12.7.4 on Windows is affected. tvOS before 11.3 is affected. watchOS before 4.3 is affected. The issue involves the "WebKit" component. It allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted web site.

Timeline

dates in UTC

2018-04-0306:29CVE publishedNVD
2018-04-09Exploit-DB entryExploit-DB

Observed activity

isMalicious corpus · updated 2026-11-03 15:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2018-4121?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2018-4121?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Apple icloudversion to verify

Branch	Affected	Fixed in	Source
7.4	< 7.4	7.4	NVD

Apple iphone os

Branch	Affected	Fixed in	Source
11.3	< 11.3	11.3	NVD

Apple itunesversion to verify

Branch	Affected	Fixed in	Source
12.7	< 12.7.4	12.7.4	NVD

3 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

accountsserviceRed Hat:enterprise_linux:7::serverall versions · fixed in 0:0.6.50-2.el7and 3 other packages
accountsserviceRed Hat:enterprise_linux:7::computenodeall versions · fixed in 0:0.6.50-2.el7and 3 other packages
accountsserviceRed Hat:enterprise_linux:7::clientall versions · fixed in 0:0.6.50-2.el7and 3 other packages
adwaita-gtk2-themeRed Hat:enterprise_linux:7::serverall versions · fixed in 0:3.28-2.el7
appstream-dataRed Hat:enterprise_linux:7::serverall versions · fixed in 0:7-20180614.el7
appstream-dataRed Hat:enterprise_linux:7::clientall versions · fixed in 0:7-20180614.el7
at-spi2-atkRed Hat:enterprise_linux:7::serverall versions · fixed in 0:2.26.2-1.el7and 2 other packages
at-spi2-atkRed Hat:enterprise_linux:7::computenodeall versions · fixed in 0:2.26.2-1.el7and 2 other packages

217 more package ranges on OSV.dev

Vendor advisories

CVE-2018-4121 Red Hat Product Security8,618 products fixed · 9 known affected
webkitgtk: memory corruption processing maliciously crafted web content
webkitgtk as a component of Red Hat Enterprise Linux 6 · webkitgtk-devel as a component of Red Hat Enterprise Linux 6 · webkitgtk-doc as a component of Red Hat Enterprise Linux 6 · +6 more
RHSA-2018:3140 Red Hat Product Security8,618 products fixed
Red Hat Security Advisory: GNOME security, bug fix, and enhancement update

Full record on NVD

Fix

Update Apple icloud to 7.4
Vendor fix Red Hat Product Security RHSA-2018:3140 · 8,618 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 GDM must be restarted for this update to take effect. The X server must be restarted (log out, then log back in) for this update to take effect. The G…
No fix planned, says the vendor Red Hat Product Security CVE-2018-4121 · 9 productsWill not fix

Advisories and patches

support.apple.comVendor Advisory
support.apple.comVendor Advisory
support.apple.comVendor Advisory
support.apple.comVendor Advisory
support.apple.comVendor Advisory
support.apple.comVendor Advisory

Detection

read 2026-11-02 22:42 UTC

Nuclei template: none so far
Exploit-DB: EDB-44427
Proof-of-concept repositories: 3 repositories, unverifiedFSecureLABS/CVE-2018-4121likekabin/CVE-2018-4121jezzus/CVE-2018-4121
Metasploit modules: none listed

Sources

NVDCVSS 3.08.8read 2026-10-23
NVDCVSS 2.06.8read 2026-10-23
NVDweakness (CWE)CWE-119read 2026-10-23
FIRST EPSSEPSS score13.1 %read 2026-11-02
PoC-in-GitHubproof of concept3read 2026-11-02
Exploit-DBdetectionread 2026-11-02
OSVaffected packages—

Identifiers

EUVD-2018-15907same flawENISA EUVD · LicenseRef-ENISA-legal-notice
RHSA-2018:3140advisory covering several CVEsRed Hat · CC-BY-4.0
SUSE-SU-2018:3387-1advisory covering several CVEsSUSE · LicenseRef-unstated

Technical details

CVSS v3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: 2018-04-03
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2018-4121?

Is CVE-2018-4121 actively exploited?

Active exploitation of CVE-2018-4121 has not been confirmed. Its EPSS score was 13.1% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-4121?

CVE-2018-4121 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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