CVE-2019-25686Public exploitNetwork attack vector

Unauthenticated service crash via oversized PBSZ command

Published Apr 5, 2026 · Updated Apr 5, 2026

Denial of service in Core FTP Server 2.0 build 653 allows remote attackers to crash the FTP service with an oversized PBSZ command. The pre-authentication PBSZ handler lets the argument overwrite ECX, then dereferences the attacker-controlled value and raises an access violation. No account or special configuration is required; one network connection can terminate the Windows server process and interrupt FTP service.

CVSS severity8.7
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Core FTP Server 2.0 build 653 allows remote attackers to crash the FTP service with an oversized PBSZ command. The pre-authentication PBSZ handler lets the argument overwrite ECX, then dereferences the attacker-controlled value and raises an access violation. No account or special configuration is required; one network connection can terminate the Windows server process and interrupt FTP service.

The record

CVE
CVE-2019-25686
Published
Apr 5, 2026
Updated
Apr 5, 2026
Vendor
Core FTP
Product
Core FTP Server
Classifications
CWE-306, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Core FTP · Core FTP Serverversion=2.0

Published CVSS scores

8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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