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CVE-2021-21178

23
FAUCET Score

CVE-2021-21178 is a medium-severity vulnerability affecting Google Chrome on Linux and Windows prior to version 89.0.4389.72, allowing a remote attacker to spoof the Omnibox (URL bar) via a crafted HTML page due to an inappropriate implementation in Compositing. The attack requires user interaction (UI:R) but can be executed remotely (AV:N), leading to a high impact on integrity (I:H) by deceiving users about the displayed URL. While there is no known public exploit code (Metasploit, Nuclei, ExploitDB) or KEV entry, the vulnerability garnered significant community discussion and media coverage, including reports of Google fixing a related actively exploited zero-day, though this specific CVE is not listed as actively exploited.

Impacted Technologies

VendorProductVersion(s)CPE
< 89.0.4389.72CPE matchmatch criteria
cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*
32CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.62%
Probability of exploitation in next 30 days
EPSS Percentile
73.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0162 is in the 86th percentile among its peer group of 26,236 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

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)

googlevendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

microsoft2021-Mar/CVE-2021-21178

Chromium CVE-2021-21178 : Inappropriate implementation in Compositing

Mar 9, 2021

References

chromereleases.googleblog.com / 2021/03/stable-channel-update-for-desktop.html
Release NotesVendor Advisory
crbug.com / 1174186
Issue TrackingPatchPermissions RequiredThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/BBT54RKAE5XLMWSHLVUKJ7T2XHHYMXLH
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/FE5SIKEVYTMDCC5OSXGOM2KRPYLHYMQX
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/LCIDZ77XUDMB2EBPPWCQXPEIJERDNSNT
security.gentoo.org / glsa/202104-08
Third Party Advisory
debian.org / security/2021/dsa-4886
Third Party Advisory