CVE-2021-40438
Apache HTTP Server-Side Request Forgery (SSRF)
IN CISA KEV
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.
- Vendor
- Apache
- Product
- Apache
- CVSS 3.1
- 9 (critical), scored by NVD (primary)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- CVSS 3.1
- 9 (critical), scored by 134c704f-9b21-4f2e-91b3-4a467353bcc0CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- CWE
- CWE-918
- Published
- 2021-09-16
- NVD modified
- 2026-08-06
- NVD status
- Analyzed
CISA KEV
- Date added
- 2021-12-01
- Due date
- 2021-12-15
- Ransomware use
- Known
- Required action
- Apply updates per vendor instructions.
EPSS
100% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- cert-portal.siemens.com (Third Party Advisory)
- httpd.apache.org (Release Notes, Vendor Advisory)
- lists.apache.org (Mailing List)
- lists.apache.org (Mailing List)
- lists.apache.org (Mailing List)
- lists.apache.org (Mailing List)
- lists.apache.org (Mailing List)
- lists.apache.org (Mailing List)
- lists.apache.org (Mailing List)
- lists.debian.org (Mailing List, Third Party Advisory)
- lists.fedoraproject.org (Release Notes)
- lists.fedoraproject.org (Release Notes)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.