How severe is CVE-2021-21111?

CVE-2021-21111 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21111 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21111?

CVE-2021-21111 primarily affects Google Chrome. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-21111?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-21111 published?

CVE-2021-21111 was published on 2021-01-08 and last updated on 2026-06-17.

CVE-2021-21111

CVE-2021-21111 is a critical-severity vulnerability in Google Chrome with a CVSS 3.x base score of 9.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1021.

Key facts

Severity: Critical (CVSS 3.x base score 9.6)
CVSS v2: 6.8
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-1021
Affected product: Google Chrome
Published: 2021-01-08
Last modified: 2026-06-17

Description

Insufficient policy enforcement in WebUI in Google Chrome prior to 87.0.4280.141 allowed an attacker who convinced a user to install a malicious extension to potentially perform a sandbox escape via a crafted Chrome Extension.

Frequently asked questions

What is CVE-2021-21111?: Insufficient policy enforcement in WebUI in Google Chrome prior to 87.0.4280.141 allowed an attacker who convinced a user to install a malicious extension to potentially perform a sandbox escape via a crafted Chrome Extension.
How severe is CVE-2021-21111?: CVE-2021-21111 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21111 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21111?: CVE-2021-21111 primarily affects Google Chrome. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-21111?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-21111 published?: CVE-2021-21111 was published on 2021-01-08 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

More vulnerabilities in Google Chrome

CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
CVE-2015-8548 — Critical (CVSS 10.0): Multiple unspecified vulnerabilities in Google V8 before 4.7.80.23, as used in Google Chrome before 47.0.2526.80, allow…
CVE-2015-6791 — Critical (CVSS 10.0): Multiple unspecified vulnerabilities in Google Chrome before 47.0.2526.80 allow attackers to cause a denial of service…
CVE-2015-6788 — Critical (CVSS 10.0): The ObjectBackedNativeHandler class in extensions/renderer/object_backed_native_handler.cc in the extensions subsystem…
CVE-2015-8480 — Critical (CVSS 10.0): The VideoFramePool::PoolImpl::CreateFrame function in media/base/video_frame_pool.cc in Google Chrome before…
CVE-2015-6787 — Critical (CVSS 10.0): Multiple unspecified vulnerabilities in Google Chrome before 47.0.2526.73 allow attackers to cause a denial of service…

All CVEs affecting Google Chrome →

Other CWE-1021 vulnerabilities

CVE-2021-43048 — Critical (CVSS 9.8): The Interior Server and Gateway Server components of TIBCO Software Inc.'s TIBCO PartnerExpress contain a vulnerability…
CVE-2021-23274 — Critical (CVSS 9.8): The Config UI component of TIBCO Software Inc.'s TIBCO API Exchange Gateway and TIBCO API Exchange Gateway Distribution…
CVE-2016-2496 — Critical (CVSS 9.8): The Framework UI permission-dialog implementation in Android 6.x before 2016-06-01 allows attackers to conduct…
CVE-2021-21132 — Critical (CVSS 9.6): Inappropriate implementation in DevTools in Google Chrome prior to 88.0.4324.96 allowed a remote attacker to…
CVE-2024-10004 — Critical (CVSS 9.1): Opening an external link to an HTTP website when Firefox iOS was previously closed and had an HTTPS tab open could in…
CVE-2023-41897 — High (CVSS 8.8): Home assistant is an open source home automation. Home Assistant server does not set any HTTP security headers,…

Browse all CWE-1021 vulnerabilities →