How severe is CVE-2018-7791?

CVE-2018-7791 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-7791 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-7791?

CVE-2018-7791 affects Schneider-electric Modicon M221 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-7791?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2018-7791 published?

CVE-2018-7791 was published on 2018-08-29 and last updated on 2026-06-17.

CVE-2018-7791

CVE-2018-7791 is a critical-severity vulnerability in Schneider-electric Modicon M221 Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Schneider-electric Modicon M221 Firmware
Published: 2018-08-29
Last modified: 2026-06-17

Description

A Permissions, Privileges, and Access Control vulnerability exists in Schneider Electric's Modicon M221 product (all references, all versions prior to firmware V1.6.2.0). The vulnerability allows unauthorized users to overwrite the original password with their password. If an attacker exploits this vulnerability and overwrite the password, the attacker can upload the original program from the PLC.

Frequently asked questions

What is CVE-2018-7791?: A Permissions, Privileges, and Access Control vulnerability exists in Schneider Electric's Modicon M221 product (all references, all versions prior to firmware V1.6.2.0). The vulnerability allows unauthorized users to overwrite the original password with their password. If an attacker exploits this vulnerability and overwrite the password, the attacker can upload the original program from the PLC.
How severe is CVE-2018-7791?: CVE-2018-7791 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-7791 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-7791?: CVE-2018-7791 affects Schneider-electric Modicon M221 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-7791?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2018-7791 published?: CVE-2018-7791 was published on 2018-08-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:schneider-electric:modicon_m221_firmware:*:*:*:*:*:*:*:*

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