Answer in brief
CVE-2021-40438 records a High severity vulnerability in mod_proxy SSRF. The current sources mark it as known exploited. The current feed maps Apache Software Foundation/Apache HTTP Server (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2021-40438 records a High severity vulnerability in mod_proxy SSRF. The current sources mark it as known exploited. The current feed maps Apache Software Foundation/Apache HTTP Server (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Apache Software Foundation/Apache HTTP Server (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Apache Software Foundation/Apache HTTP Servergeneric | Apache HTTP Server 2.4 | Not reported |
Published upstream
Sep 16, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Dec 1, 2021
Evidence: source:kev:kev:kev:recordA 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.
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Apache Software Foundation/Apache HTTP Server (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Apache Software Foundation/Apache HTTP Servergeneric | Apache HTTP Server 2.4 | Not reported |
Published upstream
Sep 16, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Dec 1, 2021
Evidence: source:kev:kev:kev:recordA 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.
Quoted source text, attributed separately from HOL analysis.