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CVE-2021-21163

22
FAUCET Score

CVE-2021-21163 is a medium-severity vulnerability affecting Google Chrome on iOS, specifically versions prior to 89.0.4389.72, as well as related products from Apple, Debian, and Fedora. This flaw, categorized as insufficient data validation (CWE-346), allowed a remote attacker to leak cross-origin data through a crafted HTML page and a malicious server. With a CVSS score of 6.5, it requires user interaction (UI:R) and has high confidentiality impact (C:H) but no integrity or availability impact. Although no public exploit code (Metasploit, Nuclei, ExploitDB) is available, this vulnerability was actively exploited as a zero-day and received significant community and media attention, including mentions on Reddit and coverage by BleepingComputer and SecurityWeek.

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:H/I:N/A:N

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

Exploit Intelligence

EPSS Score
0.94%
Probability of exploitation in next 30 days
EPSS Percentile
57.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0094 is in the 69th 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-2021-21163

Chromium CVE-2021-21163: Insufficient data validation in Reader Mode

Mar 9, 2021

References

chromereleases.googleblog.com / 2021/03/stable-channel-update-for-desktop.html
Release NotesVendor Advisory
crbug.com / 1111239
Permissions Required
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