What is CVE-2021-21134?

CVE-2021-21134 is a medium-severity vulnerability in Apple Iphone OS, classified under Authentication Bypass by Spoofing. CVSS score: 6.5/10. Published 2021-02-09.

How severe is CVE-2021-21134?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Apple Iphone OS

CVE-2021-21134

Incorrect security UI in Page Info in Google Chrome on iOS prior to 88.0.4324.96 allowed a remote attacker to spoof security UI via a crafted HTML page.

Published 2021-02-09 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.050 (92.0th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 92nd percentile — 92.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.050 · newest: 0.050 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-290 — Authentication Bypass by Spoofing

References

chromereleases.googleblog.com/2021/01/stable-channel-update-for-desktop_19.html (Release Notes, Vendor Advisory)
crbug.com/1157800 (Permissions Required, Third Party Advisory)
msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-21134 (Third Party Advisory)

Frequently asked questions

What is CVE-2021-21134?: CVE-2021-21134 is a medium-severity vulnerability in Apple Iphone OS, classified under Authentication Bypass by Spoofing. CVSS score: 6.5/10. Published 2021-02-09.
How severe is CVE-2021-21134?: Medium severity. CVSS v3 base score is 6.5 out of 10.