CVE-2021-4138

MEDIUM 5.3CVE-2021-4138 · Published 02/05/2022 · updated 17/06/2026

In short

CVE-2021-4138 is a MEDIUM (CVSS 5.3) vulnerability affecting geckodriver (mozilla).
Chance of exploitation in the next 30 days (EPSS): 0.85%, higher than 58.3% of all vulnerabilities.
Fix: update to 0.30.0 or later.

Package	Affected versions	Patched versions
geckodriver mozilla	`< 0.30.0`	`0.30.0`

Improved Host header checks to reject requests not sent to a well-known local hostname or IP, or the server-specified hostname.

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