How severe is CVE-2021-21806?

CVE-2021-21806 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21806 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21806?

CVE-2021-21806 affects Webkitgtk. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21806?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-21806 published?

CVE-2021-21806 was published on 2021-07-08 and last updated on 2026-06-17.

CVE-2021-21806

CVE-2021-21806 is a high-severity vulnerability in Webkitgtk with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 3% (85th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Webkitgtk
Published: 2021-07-08
Last modified: 2026-06-17

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.

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.
How severe is CVE-2021-21806?: CVE-2021-21806 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21806 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21806?: CVE-2021-21806 affects Webkitgtk. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21806?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-21806 published?: CVE-2021-21806 was published on 2021-07-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:webkitgtk:webkitgtk:2.30.3:*:*:*:*:*:x64:*

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CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
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