basicsecurity.net
Proof, not just disclosure.
Threats / CrushFTP / CVE-2024-4040
CVE-2024-4040 · EUVD no mirror located · GCVE no mirror located Verified 2026-06-22

CrushFTP vulnerability

CrushFTP contains a sandbox escape vulnerability allowing remote attackers to bypass the virtual file system (VFS) restrictions and access the underlying host system.

Verdict

Today item — known-exploited.

A remote attacker can exploit this unspecified sandbox escape to break out of CrushFTP's VFS isolation, potentially gaining unauthorized access to files and system resources beyond the intended restricted scope.

CISA KEV Yes · 2024-04-243EPSS 0.99539 (verify live)4Exploit Weaponized · public PoC5
01

Is it exploitable?

— the evidence, ranked above the score
Exploit 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
194 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 2024-04-24).
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.99539 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: CrushFTP, CrushFTP. Confirm exact fixed builds in the vendor advisory.
NVD ↗Reported
Weakness (CWE)
Mapped to CWE-1336 Template Injection — weakness family: Injection.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
NVD ↗Reported
02

Who’s exploiting it?

— attribution turns risk into urgency
Attribution 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 board
1

Front door — unauthenticated access narrative 1

Attacker
I craft a malicious request that exploits the sandbox escape flaw in CrushFTP's VFS boundary enforcement.
Business
The organization's file server is exposed to unauthorized data access and exfiltration beyond configured access controls.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I execute commands or access filesystem paths outside the virtual environment that CrushFTP is designed to restrict.
Business
Sensitive files, credentials, and system configuration become accessible to the attacker, compromising confidentiality and integrity.
3

Lateral reach — past segmentation narrative 3

Attacker
I leverage the escaped context to move laterally within the host system or establish persistence.
Business
The breach scope expands beyond the FTP service to the underlying infrastructure, increasing incident response costs and recovery time.
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

Coverage & confidence

— what we know, and what we don’t

Established (cited)

  • KEV listing (CISA)
  • EPSS probability (FIRST)
  • Weaponized exploit available (VulnCheck)
  • 194 reported-exploitation source(s)
  • CWE weakness mapping (NVD)
  • Public exploit availability
  • Catalogued by directcyber (CNA)
  • Named finder/reporter credit (CVE.org)
  • Coverage gaps — stated, not hidden

  • No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.
  • EPSS & exposure are time-varying; verify live at the source.
  • Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.
  • Disclosure & credit2
    Catalogued by directcyberCNA