Threadlinqs IntelligenceStart free

VulnerabilityCVE-2021-37973Published 2021-10-08

CVE-2021-37973 — Google Chrome

criticalCISA KEVPublic exploit1 PoC repo

As of 2025-10-21, CVE-2021-37973 is a CRITICAL-severity vulnerability in Google Chrome, CVSS v3.1 9.6, EPSS 11.7% (95.9th 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”.

CVSS v3.1
9.6/10Critical
EPSS
11.7%Higher than 95.9% of scored CVEs
CISA KEV
ListedAdded · due 2021-11-17
Tracked threats
1Campaigns referencing it
Priority
9/10Threadlinqs triage score
Published
Updated 2025-10-21
CVSS v3.1 9.6 (CRITICAL) · EPSS 11.7% (higher than 95.9% of all scored CVEs) · Priority 9/10 · Published 2021-10-08

Last updated:

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 1850 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)
11.7% probability of exploitation in the next 30 days, higher than 95.9% 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 2025-10-21

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. Weaponised exploit code for CVE-2021-37973 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 47 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. Patch reference: https://crbug.com/1251727. 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

Enriched from CVE.org, NVD, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch

Other references