CVE-2017-7901

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

9.0% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2017-06-30 03:29 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 01:25 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 9.0% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2017-06-30 03:29 UTC

Last modified

2026-06-17 01:25 UTC

Exploit probability

9.0% · EPSS, next 30 days

Weakness

CWE-343

Record status

Modified

Affected

• Rockwellautomation 1763-l16awa Series A ≤ 16.000
• Rockwellautomation 1763-l16awa Series B ≤ 16.000
• Rockwellautomation 1763-l16bbb Series A ≤ 16.000
• Rockwellautomation 1763-l16bbb Series B ≤ 16.000
• Rockwellautomation 1763-l16bwa Series A ≤ 16.000
• Rockwellautomation 1763-l16bwa Series B ≤ 16.000
• Rockwellautomation 1763-l16dwd Series A ≤ 16.000
• Rockwellautomation 1763-l16dwd Series B ≤ 16.000

Attack profile CVSS 3.0 · 8.6

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

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