Improved Host header checks to reject requests not sent to a well-known local hostname or…
Priority LOW 26Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
Improved Host header checks to reject requests not sent to a well-known local hostname or IP, or the server-specified hostname.
Why it matters now
EPSS 0.00847 58th percentileScored 2026-11-07
Fix Fixed geckodriver (Mozilla): 0.30.0
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA geckodriver (Mozilla) Fixed in 0.30.0
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 1 product
- Red Hat Advanced Cluster Management for Kubernetes 2
Timeline
- 2026-10-02 Threatist record created from CVE-2021-4138
- 2026-10-03 Alias added: GHSA-2h28-m3qw-8www
References
More Mozilla Geckodriver vulnerabilities
- TI-2020-12335 Missing checks on Content-Type headers in geckodriver before 0.27.0 could lead to a CSRF… CVSS 3.1HIGH 8.8
Sources
- CVE-2021-4138 · CVE Program
- CVE-2021-4138 · NVD
- FIRST EPSS
- GHSA-2h28-m3qw-8www · GitHub Advisory Database · CC BY 4.0
- CVE-2021-4138 · Red Hat security data · CC BY 4.0
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