CVE-2024-21785Public exploitNetwork attack vector

Unauthenticated diagnostic access via predictable daily key

Published May 28, 2024 · Updated Feb 13, 2025

Active debug code in the Telnet interface of AutomationDirect P3-550E 1.2.10.9 allows remote attackers to gain unauthorized access. The lock_telnet routine accepts a seven-character daily key derived by a weak algorithm from the device date and MAC address exposed by MACBORG. Network access to the default-enabled Telnet service is sufficient to enter PCMON and read or modify memory and files or change PLC run state.

CVSS severity9.8
Critical
EPSS probability1.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Active debug code in the Telnet interface of AutomationDirect P3-550E 1.2.10.9 allows remote attackers to gain unauthorized access. The lock_telnet routine accepts a seven-character daily key derived by a weak algorithm from the device date and MAC address exposed by MACBORG. Network access to the default-enabled Telnet service is sufficient to enter PCMON and read or modify memory and files or change PLC run state.

The record

CVE
CVE-2024-21785
Published
May 28, 2024
Updated
Feb 13, 2025
Vendor
AutomationDirect
Product
P3-550E
Classifications
CWE-489, T0819
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=1.2.10.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

AutomationDirect · P3-550Eversion=1.2.10.9

Published CVSS scores

9.8Cisco TalosCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3AutomationDirectCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-489Leftover Debug Code
T0819Exploit Public-Facing Application

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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