CVE-2017-7901
Insufficiently random TCP initial sequence numbers are generated, which may allow an attacker to predict the numbers from previous values.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (9.05%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.0
- 8.6 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
- EPSS
- 9.05% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-343, CWE-330
- Affected
- rockwellautomation/1763-l16awa series a · rockwellautomation/1763-l16awa series b · rockwellautomation/1763-l16bbb series a · rockwellautomation/1763-l16bbb series b · rockwellautomation/1763-l16bwa series a · rockwellautomation/1763-l16bwa series b · rockwellautomation/1763-l16dwd series a · rockwellautomation/1763-l16dwd series b · rockwellautomation/1766-l32awa series a · rockwellautomation/1766-l32awa series b · rockwellautomation/1766-l32awaa series a · rockwellautomation/1766-l32awaa series b · rockwellautomation/1766-l32bwa series a · rockwellautomation/1766-l32bwa series b · rockwellautomation/1766-l32bwaa series a · rockwellautomation/1766-l32bwaa series b · rockwellautomation/1766-l32bxb series a · rockwellautomation/1766-l32bxb series b · rockwellautomation/1766-l32bxba series a · rockwellautomation/1766-l32bxba series b
- Source
- ics-cert@hq.dhs.gov
EPSS moved from 9.6% on 21 September 2026 to 9.0% on 27 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
References
- http://www.securitytracker.com/id/1038546
- https://ics-cert.us-cert.gov/advisories/ICSA-17-115-04Patch, Third Party Advisory, US Government Resource
- http://www.securitytracker.com/id/1038546
- https://ics-cert.us-cert.gov/advisories/ICSA-17-115-04Patch, Third Party Advisory, US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.