Threats / Apache / CVE-2021-41773
CVE-2021-41773
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Apache HTTP Server vulnerability
Apache HTTP Server path traversal vulnerability allowing remote code execution when Alias directives lack proper access controls or CGI is enabled. Actively exploited with ransomware deployment.
Verdict
Today item, not a backlog item.
Critical path traversal flaw enabling unauthenticated remote code execution on vulnerable Apache servers. Initial patch insufficient; CVE-2021-42013 addresses bypass. High real-world exploitation activity with ransomware campaigns documented.
CISA KEV Yes · 2021-11-033Ransomware use Flagged3EPSS 0.99992 (verify live)4Exploit Weaponized · public PoC5
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
294 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.99992 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Apache, HTTP Server. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-22 Path Traversal — weakness family: Path traversal / file.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft HTTP requests with path traversal sequences to access files outside configured Alias directories.
Business
Attacker gains unauthorized file system access on the web server.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I locate and execute CGI scripts or write malicious scripts to arbitrary locations on the server.
Business
Attacker achieves remote code execution with web server privileges.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistence and deploy ransomware or data exfiltration payloads across the infrastructure.
Business
Organization experiences operational shutdown, data loss, and financial extortion demands.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05