Schneider Electric Modicon Modbus Protocol Authentication Bypass by Capture-replay

published 2017-06-30 9 y ago modified 2026-06-17 4 mo ago also EUVD-2017-15102

cvss: 9.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 5.6%; EPSS 5.6% chance of exploitation in 30 days, percentile 92%
public exploits: 0; none known

An authentication bypass by capture-replay issue was discovered in Schneider Electric Modicon Modbus Protocol. Sensitive information is transmitted in cleartext in the Modicon Modbus protocol, which may allow an attacker to replay the following commands: run, stop, upload, and download.

Vendor advisories

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

cisa ICSA-17-101-01 updated 2017-04-11 cvss 10.0

Schneider Electric Modicon Modbus Protocol

Schneider Electric Software, LLC Modicon Modbus protocol
affected: mitigation “Protect access to M1E controllers by a firewall blocking all remote/external access to Port 502.”

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

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: total
Assessed: 5 mo ago (2026-05-28)

Exploit prediction

5.60% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	3.0	9.8	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

Schneider Electric Modicon Modbus Protocol

Classification

Weakness

CWE-294 Authentication Bypass by Capture-replay
CWE-287 Improper Authentication

References

ics-cert.us-cert.gov /advisories/ICSA-17-101-01
third-party-advisory, us-government-resource
securityfocus.com /bid/97562
vdb-entry, third-party-advisory
github.com /cisagov/CSAF/blob/develop/csaf_files/OT/white/2017/icsa-17-101-01.json
se.com /us/en/download/document/SEVD-2017-065-01/

Sources

CVE List CVE-2017-6034
NVD CVE-2017-6034

Fencer Vulns 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.

Summary