CyberSecBulletin
CVE-2025-54309Exploited in the wildNVD status: Analyzed

CrushFTP Unprotected Alternate Channel

Published Updated By the CyberSecBulletin desk

CVE-2025-54309 is a critical-severity unprotected alternate channel vulnerability in CrushFTP, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 10.8.5, 11.3.4_23 as the first without the flaw, so updating CrushFTP to one of those releases or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on July 22, 2025, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update CrushFTP to 10.8.5 or 11.3.4_23, whichever matches your release line, or a later version.
  2. CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  3. Read the advisory on crushftp.com for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
CrushFTPCrushFTP10 up to, but not including, 10.8.5; 11 up to, but not including, 11.3.4_2310.8.5, 11.3.4_23

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.0CriticalCNA (mitre.org)
CVSS 3.19.8CriticalNVD

Official description

CrushFTP 10 before 10.8.5 and 11 before 11.3.4_23, when the DMZ proxy feature is not used, mishandles AS2 validation and consequently allows remote attackers to obtain admin access via HTTPS, as exploited in the wild in July 2025.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Unprotected Alternate Channel

The product protects a primary channel, but it does not use the same level of protection for an alternate channel.

How developers prevent this class of flaw

  • Identify all alternate channels and use the same protection mechanisms that are used for the primary channels.

More Unprotected Alternate Channel vulnerabilities (CWE-420)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in CrushFTP

All CrushFTP vulnerabilities

Recent Unprotected Alternate Channel vulnerabilities

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