CVE-2021-40438
CISA KEVPublished December 1, 2021 · Updated April 3, 2026
high
Official Description+
A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.
Affected Products
| Vendor | Product |
|---|---|
| Apache | Apache |
Patch Status
Patch by 2021-12-15
Recommended Actions
- Check if your systems use any of the affected products listed above.
- Apply vendor patches immediately if available.
- This vulnerability is in CISA's Known Exploited Vulnerabilities catalog — prioritize remediation.
- Monitor vendor advisories for updates and additional mitigations.
- Review logs for indicators of compromise related to CVE-2021-40438.