Schneider Electric Modicon PLCs Predictable Value Range from Previous Values
Published Jun 30, 2017
6.5
MEDIUMCVSS 3.1
EPSS 2.14%
Description
A predictable value range from previous values issue was discovered in Schneider Electric Modicon PLCs Modicon M221, firmware versions prior to Version 1.5.0.0, Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11. The affected products generate insufficiently random TCP initial sequence numbers that may allow an attacker to predict the numbers from previous values. This may allow an attacker to spoof or disrupt TCP connections.
Affected products
-
- Version 0StatusaffectedConstraints<1.5.0.0
- Version
-
- Version 0StatusaffectedConstraints<4.0.5.11
- Version
-
- Version 0StatusaffectedConstraints<4.0.5.11
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Schneider Electric | Modicon M221 | unaffected |
| ||||||
| Schneider Electric | Modicon M241 | unaffected |
| ||||||
| Schneider Electric | Modicon M251 | unaffected |
|
Configuration 1
- ≤ 4.0.3.20
Running on/with
- n/a
Configuration 2
- ≤ 4.0.3.20
Running on/with
- n/a
Configuration 3
- ≤ 1.1.1.5
Running on/with
- n/a
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
Vendor solution
Schneider Electric has released new firmware versions to address the predictable value range from previous values vulnerability and the use of insufficiently random values vulnerability, which are available through Schneider Electric’s software update tool, SoMachine, Version 4.2, and SoMachineBasic, Version 1.5. Schneider Electric has not released a product to address the insufficiently protected credentials vulnerability; however, Schneider Electric has provided compensating controls to reduce the risk of exploitation.
SoMachineBasic, Version 1.5, is available at the following location:
http://www.schneider-electric.fr/fr/download/document/SOMBASAP15SOFT/
Schneider Electric has provided the following compensating controls to reduce the risk of exploitation of the insufficiently protected credentials vulnerability:
* Verify that the hardware and software infrastructure that the PLCs are integrated into (along with all organizational measures and rules covering access to the infrastructure) consider the results of the hazard and risk analysis, and are implemented according to best practices and standards such as ISA/IEC 62443. * Limit traffic on the local network with managed switches * Where possible, avoid using Wi-Fi networks, but when Wi-Fi is essential, use only secure communications (such as WPA2 encryption) * Do not grant [network] access to unknown computers * When remote access is essential, use secure methods such as Virtual Private Networks (VPNs), and ensure the remote access solution(s), as well as the remote computer(s) are kept up-to-date with the latest security patches.
Schneider Electric has released Security Notifications SEVD-2017-075-01, SEVD-2017-075-02, and SEVD-2017-075-03, which provide additional information about the identified vulnerabilities, mitigations, and compensating controls:
http://www.schneider-electric.com/en/download/document/SEVD-2017-075-01/
http://www.schneider-electric.com/en/download/document/SEVD-2017-075-02/
http://www.schneider-electric.com/en/download/document/SEVD-2017-075-03/
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
No CVSS v3.0 score for this CVE.
AV:N/AC:L/Au:N/C:N/I:P/A:P
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
YesTechnical Impact
PartialDecision
n/aAssessed May 29, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
Percentile over time
- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
Table of values (10 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 2.14% (0.02142) | 81.39th | v5 (v2026.06.15) |
| Jun 15, 2026 | 2.12% (0.02124) | 79.44th | v5 (v2026.06.15) |
| Jul 20, 2024 | 0.08% (0.00085) | 36.68th | v3 (v2023.03.01) |
| Sep 3, 2023 | 0.08% (0.00085) | 35.06th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.08% (0.00079) | 32.16th | v3 (v2023.03.01) |
| Mar 6, 2023 | 0.89% (0.00885) | 27.89th | v2 (v2022.01.01) |
| Oct 11, 2021 | 0.62% (0.00624) | 45.37th | v1 |
| Oct 10, 2021 | 2.74% (0.02742) | 80.22th | v5 (v2026.06.15) |
| Aug 20, 2021 | 2.74% (0.02742) | 0.00th | v1 |
| Apr 14, 2021 | 0.62% (0.00624) | 0.00th | v1 |
References (3)
- http://www.securityfocus.com/bid/97254 vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
- https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2017/icsa-17-089-02.json
- https://ics-cert.us-cert.gov/advisories/ICSA-17-089-02 x_refsource_MISCThird Party AdvisoryUS Government Resource
| Link | Providers | Tags |
|---|---|---|
| http://www.securityfocus.com/bid/97254 | vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry | |
| https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2017/icsa-17-089-02.json | ||
| https://ics-cert.us-cert.gov/advisories/ICSA-17-089-02 | x_refsource_MISCThird Party AdvisoryUS Government Resource |
Change history (0)
No recorded changes yet.