Threat Intelligence / CVE / CVE-2021-37973

CVE-2021-37973 — Google Chrome

CISA KEV
CVSS v3.1 9.6 (CRITICAL) · EPSS 6.4% (higher than 91.1% of all scored CVEs) · Priority 9/10 · Published 2021-10-08

As of 2025-10-24, CVE-2021-37973 is a CRITICAL-severity vulnerability in Google Chrome, CVSS v3.1 9.6, EPSS 6.4% (91.1th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), with a US federal remediation deadline of 2021-11-17. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2021-37973, most recently “Hack-for-Hire Espionage Campaign Targeting MENA Civil Society via Predator/Intellexa Mercenary Spyware”.

Last updated: 2025-10-24

What is CVE-2021-37973?

Use after free in Portals in Google Chrome prior to 94.0.4606.61 allowed a remote attacker who had compromised the renderer process to potentially perform a sandbox escape via a crafted HTML page.

The record classifies CVE-2021-37973 under weakness class CWE-416. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 5 affected-product entries are recorded, across 3 vendors, listed below. The identifier was first published 1801 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.6 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
EPSS (FIRST)
6.4% probability of exploitation in the next 30 days, higher than 91.1% of all scored CVEs
CISA KEV
Listed since 2021-11-03, federal remediation deadline 2021-11-17
Threadlinqs priority
9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published
2021-10-08, last modified 2025-10-24

Is CVE-2021-37973 being exploited?

CISA added CVE-2021-37973 to the Known Exploited Vulnerabilities catalog on 2021-11-03, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2021-11-17 under BOD 22-01. It currently carries a trending score of 38 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2021-37973

The record marks a vendor fix as available for CVE-2021-37973. Vendor advisory: https://chromereleases.googleblog.com/2021/09/stable-channel-update-for-desktop_24.html. Because CVE-2021-37973 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2021-11-17. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2021-37973

1 tracked threat in the Threadlinqs corpus references CVE-2021-37973, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2021-37973 are available via the Threadlinqs MCP server (Purple tier). View plans →

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