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Fencer Vulns
high 8.8

CVE-2021-21206 kev in the critical feed json

Use after free in Blink in Google Chrome prior to 89.0.4389.128 allowed a remote attacker to potentially exploit heap corruption via a craf…

published 2021-04-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-8597

cvss
8.8
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03
epss
9.3%
EPSS 9.3% chance of exploitation in 30 days, percentile 95%
public exploits
0
none known

Summary

Use after free in Blink in Google Chrome prior to 89.0.4389.128 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

Patch / fix

cisa required action Apply updates per vendor instructions.

  • Google Chrome 89.0.4389.128
  • chromium Debian 14, Debian 13, Debian 12 90.0.4430.72-1

debian advisories DEBIAN-CVE-2021-21206

  • chromium-browser Ubuntu 16.04 LTS 90.0.4430.72-0ubuntu0.16.04.1
  • chromium-browser Ubuntu 18.04 LTS 90.0.4430.72-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2021-21206

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • chromium openSUSE Tumbleweed 93.0.4577.82-1.1
  • chromium openSUSE Tumbleweed 113.0.5672.92-1.1
  • opera openSUSE Leap 15.2 NonFree 76.0.4017.94-lp152.2.43.1
  • chromium Package Hub 15 SP2 89.0.4389.128-bp152.2.71.1
  • chromium openSUSE Leap 15.2 89.0.4389.128-lp152.2.86.1

opensuse advisories openSUSE-SU-2024:10681-1openSUSE-SU-2024:12948-1openSUSE-SU-2021:0712-1openSUSE-SU-2021:0575-1openSUSE-SU-2021:0567-1

  • chromium Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 89.0.4389.128-r0
  • qt5-qtwebengine Alpine 3.23, Alpine 3.22, Alpine 3.21 +7 more 5.15.3_git20210510-r0

alpine advisories ALPINE-CVE-2021-21206

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • chromium Arch Linux 89.0.4389.128-1
  • vivaldi Arch Linux 3.7.2218.55-1

arch linux advisories AVG-1816AVG-1817

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-21206 updated cvss 8.8

chromium-browser: Use after free in Blink

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. Found exploited as a 0-day (Project Zero)
  2. 0-day patched (Project Zero)
  3. Published
  4. Added to CISA KEV
  5. CISA patch deadline
  6. CISA SSVC: exploitation active

Known exploited

Added
5 y ago
Patch by
2021-11-17 (4 y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
Google, Chromium Blink
CISA name
Google Chromium Blink Use-After-Free Vulnerability

Zero-day

Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.

Found
2021-04-07
Patched
2021-04-13
Details
project zero tracker

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1059.007 JavaScript exploitation
  • T1203 Exploitation for Client Execution exploitation

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
total
Assessed
21 mo ago

Exploit prediction

9.31% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • Google Chrome

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.