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Google · Chromium

CVE-2021-21166

Google Chromium Race Condition Vulnerability

CISA KEV record

CISA date added
2021-11-03
CISA due date
2021-11-17
Known ransomware use
Unknown

NVD risk context

8.8 HIGH

CVSS is a technical severity score. CISA’s KEV status remains the evidence that this vulnerability is known to be exploited.

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Attack vector
Network
The vulnerable service can be reached remotely over a network.
Attack complexity
Low
Exploitation does not require unusual conditions beyond normal attacker control.
Privileges required
None
The attacker does not need an existing account or privileges.
User interaction
Required
A user must take an action, such as opening a file or link.

Description

Google Chromium contains a race condition vulnerability that allows a remote attacker to potentially exploit heap corruption via a crafted HTML page. This vulnerability could affect multiple web browsers that utilize Chromium, including, but not limited to, Google Chrome, Microsoft Edge, and Opera.

Required action

Apply updates per vendor instructions.

NVD reference index

Vendor and remediation references

NVD has tagged these sources as vendor advisories, patches, mitigations, or release notes.

Other NVD references (4)

MITRE CWE context

CWE classification

CWE-122 Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

View official MITRE CWE details ↗
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

View official MITRE CWE details ↗

NVD record timing

NVD record timeline

These dates describe NVD’s record, not CISA’s KEV addition or remediation due date.

NVD published
Mar 09, 2021, 06:15 PM UTC
When NVD first published this CVE record.
NVD last updated
Jun 17, 2026, 03:34 AM UTC
When NVD last changed its analysis or record data.
Advanced: view the technical CVSS vector

This standardized code is intended for security tools and technical analysts. The plain-language risk summary above explains its main points.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

View NVD record ↗

CISA notes

https://nvd.nist.gov/vuln/detail/CVE-2021-21166