What’s Vulnerable › Vulnerabilities

CVE-2021-21126

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 8.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-02-09 · updated 2026-06-17
• Weakness: CWE-20

Description

Insufficient policy enforcement in extensions in Google Chrome prior to 88.0.4324.96 allowed a remote attacker to bypass site isolation via a crafted Chrome Extension.

Affected products

• Google Chrome: before 88.0.4324.96 — fixed in 88.0.4324.96
• Microsoft Edge (Chromium): before 88.0.705.50 — fixed in 88.0.705.50
• Google Chrome: before 88.0.4324.96 — fixed in 88.0.4324.96

How to fix

Upgrade to a fixed version: Google Chrome 88.0.4324.96; Microsoft Edge (Chromium) 88.0.705.50; Google Chrome 88.0.4324.96. Check the vendor advisory for mitigations.

References

• https://chromereleases.googleblog.com/2021/01/stable-channel-update-for-desktop_19.html
• https://crbug.com/1108126
• https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-21126
• https://chromereleases.googleblog.com/2021/01/stable-channel-update-for-desktop_19.html
• https://crbug.com/1108126
• https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-21126

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