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Fencer Intel
high 8.6

CVE-2017-7901 json

A Predictable Value Range from Previous Values issue was discovered in Rockwell Automation Allen-Bradley MicroLogix 1100 programmable-logic…

published 2017-06-30 9 y ago modified 2026-06-17 4 mo ago also EUVD-2017-16872

cvss
8.6
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
9.0%
EPSS 9.0% chance of exploitation in 30 days, percentile 95%
public exploits
0
none known

Summary

A Predictable Value Range from Previous Values issue was discovered in Rockwell Automation Allen-Bradley MicroLogix 1100 programmable-logic controllers 1763-L16AWA, Series A and B, Version 16.00 and prior versions; 1763-L16BBB, Series A and B, Version 16.00 and prior versions; 1763-L16BWA, Series A and B, Version 16.00 and prior versions; and 1763-L16DWD, Series A and B, Version 16.00 and prior versions and Allen-Bradley MicroLogix 1400 programmable logic controllers 1766-L32AWA, Series A and B, Version 16.00 and prior versions; 1766-L32BWA, Series A and B, Version 16.00 and prior versions; 1766-L32BWAA, Series A and B, Version 16.00 and prior versions; 1766-L32BXB, Series A and B, Version 16.00 and prior versions; 1766-L32BXBA, Series A and B, Version 16.00 and prior versions; and 1766-L32AWAA, Series A and B, Version 16.00 and prior versions. Insufficiently random TCP initial sequence numbers are generated, which may allow an attacker to predict the numbers from previous values. This may allow an attacker to spoof or disrupt TCP connections, resulting in a denial of service for the target device.

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-17-115-04 updated cvss 5.4

Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400

  • Rockwell Automation 1763-L16AWA Series A and B <= 16.00 Rockwell Automation 1763-L16BBB Series A and B <= 16.00 Rockwell Automation 1763-L16BWA Series A and B <= 16.00 Rockwell Automation 1763-L16DWD Series A and B <= 16.00 Rockwell Automation 1766-L32AWA Series A and B <= 16.00 Rockwell Automation 1766-L32AWAA Series A and B <= 16.00
    +4 more products
    Rockwell Automation 1766-L32BWA Series A and B <= 16.00 Rockwell Automation 1766-L32BWAA Series A and B <= 16.00 Rockwell Automation 1766-L32BXB Series A and B <= 16.00 Rockwell Automation 1766-L32BXBA Series A and B <= 16.00
    affected: mitigation “Rockwell Automation's new firmware version for the Allen-Bradley MicroLogix 1400 Series B controllers, FRN 21.00” rockwellautomation.custhelp.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

Exploit prediction

9.05% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 8.6 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
NVD 2.0 9.0 AV:N/AC:L/Au:N/C:P/I:P/A:C

Affected products

  • n/a Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400

Classification

Weakness
  • CWE-343 Predictable Value Range from Previous Values
  • CWE-330 Use of Insufficiently Random Values

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.