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HIGH

CVE-2021-21806

CVSS v3

8.8

HIGH

EPSS Score

2.8 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • accountsserviceAlmaLinux:8all versions · fixed in 0.6.55-2.el8and 2 other packages
  • gdmAlmaLinux:8all versions · fixed in 1:40.0-15.el8
  • gnome-autoarAlmaLinux:8all versions · fixed in 0.2.3-2.el8
  • gnome-calculatorAlmaLinux:8all versions · fixed in 3.28.2-2.el8
  • gnome-classic-sessionAlmaLinux:8all versions · fixed in 3.32.1-20.el8and 23 other packages
  • gnome-control-centerAlmaLinux:8all versions · fixed in 3.28.2-28.el8and 1 other package
  • gnome-online-accountsAlmaLinux:8all versions · fixed in 3.28.2-3.el8and 1 other package
  • gnome-sessionAlmaLinux:8all versions · fixed in 3.28.1-13.el8and 3 other packages

9 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-21806 Red Hat Product Security70 products fixed · 9 known affected

    webkitgtk: Use-after-free in fireEventListeners leading to arbitrary code execution

    webkitgtk as a component of Red Hat Enterprise Linux 6 · webkitgtk-devel as a component of Red Hat Enterprise Linux 6 · webkitgtk-doc as a component of Red Hat Enterprise Linux 6

  • RHSA-2025:10364 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: webkitgtk4 security update

  • RHSA-2021:4381 Red Hat Product Security46 products fixed

    Red Hat Security Advisory: GNOME security, bug fix, and enhancement update

Full record on NVD

Description

An exploitable use-after-free vulnerability exists in WebKitGTK browser version 2.30.3 x64. A specially crafted HTML web page can cause a use-after-free condition, resulting in remote code execution. The victim needs to visit a malicious web site to trigger the vulnerability.

Technical details

Published
2021-07-08

Frequently asked questions

What is CVE-2021-21806?

An exploitable use-after-free vulnerability exists in WebKitGTK browser version 2.30.3 x64. A specially crafted HTML web page can cause a use-after-free condition, resulting in remote code execution. The victim needs to visit a malicious web site to trigger the vulnerability.

Is CVE-2021-21806 actively exploited?

Active exploitation of CVE-2021-21806 has not been confirmed. Its EPSS score was 2.8% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-21806?

CVE-2021-21806 has a CVSS v3 base score of 8.8 (HIGH severity).

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