CVE-2017-6026Schneider Electric Modicon PLCs Vulnerability
A Use of Insufficiently Random Values issue was discovered in Schneider Electric Modicon PLCs Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11.
Published Jun 30, 2017 · Updated May 12, 2026
Key Facts
Patch immediately- CVE-2017-6026 is a critical-severity vulnerability (CVSS 9.1 v3.1) affecting Modicon M241 Firmware (Schneider-Electric), Modicon M251 Firmware (Schneider-Electric), Schneider Electric Modicon PLCs.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 32% probability of exploitation in the next 30 days.
- Fixed versions are available, including Modicon M241 Firmware 4.0.3.20, Modicon M251 Firmware 4.0.3.20.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Scores
CVSS v3.1
9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS (30-day exploit likelihood)
32%
Higher than 98.2% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
45/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
2
Proof-of-concept links
In-the-wild evidence
0
Reports of active use
Advisories And Exploit References
- advisoryhttps://ics-cert.us-cert.gov/advisories/ICSA-17-089-02
- advisory97254
Description
A Use of Insufficiently Random Values issue was discovered in Schneider Electric Modicon PLCs Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11. The session numbers generated by the web application are lacking randomization and are shared between several users. This may allow a current session to be compromised.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Modicon M241 FirmwareSchneider-Electric | See advisory | 4.0.3.20 |
| Modicon M251 FirmwareSchneider-Electric | See advisory | 4.0.3.20 |
| Schneider Electric Modicon PLCs | >= Schneider Electric Modicon PLCs | n/a |
Patched Releases
Modicon M241 Firmware
4.0.3.20
Modicon M251 Firmware
4.0.3.20
Timeline
Publicly disclosed
Jun 30, 2017
Last updated
May 12, 2026
Weakness Type
- CWE-330 Use of Insufficiently Random Values
References
- advisoryics-cert.us-cert.gov · ICSA-17-089-02
- advisory97254
- exploitExploitDB-45918
- exploit45918
FAQ
Common Questions.
A Use of Insufficiently Random Values issue was discovered in Schneider Electric Modicon PLCs Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11.
Affected: Modicon M241 Firmware (Schneider-Electric); Modicon M251 Firmware (Schneider-Electric); Schneider Electric Modicon PLCs versions >= Schneider Electric Modicon PLCs. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Modicon M241 Firmware 4.0.3.20, Modicon M251 Firmware 4.0.3.20.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Is CVE-2017-6026 On Your Attack Surface?
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