What is CVE-2021-1826?

CVE-2021-1826 is a medium-severity vulnerability in Apple iOS And Ipados, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-09-08.

How severe is CVE-2021-1826?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Apple iOS And Ipados

CVE-2021-1826

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.3, iOS 14.5 and iPadOS 14.5, watchOS 7.4, tvOS 14.5. Processing maliciously crafted web content may lead to universal cross site scripting.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-09-08 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.011 (65.5th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 65.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Apple iOS And Ipados — versions unspecified
Apple Ipados
Apple Iphone OS
Apple macOS — versions unspecified
Apple tvOS — versions unspecified
Apple watchOS — versions unspecified

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

support.apple.com/en-us/HT212317 (Vendor Advisory)
support.apple.com/en-us/HT212323 (Vendor Advisory)
support.apple.com/en-us/HT212324 (Vendor Advisory)
support.apple.com/en-us/HT212325 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-1826?: CVE-2021-1826 is a medium-severity vulnerability in Apple iOS And Ipados, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-09-08.
How severe is CVE-2021-1826?: Medium severity. CVSS v3 base score is 6.1 out of 10.