How severe is CVE-2018-7831?

CVE-2018-7831 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-7831 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-7831?

CVE-2018-7831 primarily affects Schneider-electric Modicom M340 Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-7831?

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

When was CVE-2018-7831 published?

CVE-2018-7831 was published on 2018-11-30 and last updated on 2026-06-17.

CVE-2018-7831

CVE-2018-7831 is a high-severity vulnerability in Schneider-electric Modicom M340 Firmware with a CVSS 3.x base score of 8.8. 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-79.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 4.3
EPSS exploit prediction: 1% (46th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Schneider-electric Modicom M340 Firmware
Published: 2018-11-30
Last modified: 2026-06-17

Description

An Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 allowing an attacker to send a specially crafted URL to a currently authenticated web server user to execute a password change on the web server.

Frequently asked questions

What is CVE-2018-7831?: An Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 allowing an attacker to send a specially crafted URL to a currently authenticated web server user to execute a password change on the web server.
How severe is CVE-2018-7831?: CVE-2018-7831 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-7831 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-7831?: CVE-2018-7831 primarily affects Schneider-electric Modicom M340 Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-7831?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-7831 published?: CVE-2018-7831 was published on 2018-11-30 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:schneider-electric:modicom_m340_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:schneider-electric:modicom_premium_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:schneider-electric:modicom_quantum_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:schneider-electric:modicom_bmxnor0200h_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Schneider-electric Modicom M340 Firmware

CVE-2018-7811 — Critical (CVSS 9.8): An Unverified Password Change vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum…
CVE-2018-7809 — Critical (CVSS 9.8): An Unverified Password Change vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum…
CVE-2018-7833 — High (CVSS 7.5): An Improper Check for Unusual or Exceptional Conditions vulnerability exists in the embedded web servers in all Modicon…
CVE-2018-7812 — High (CVSS 7.5): An Information Exposure through Discrepancy vulnerability exists in the embedded web servers in all Modicon M340,…
CVE-2018-7830 — High (CVSS 7.5): Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') vulnerability exists in the…
CVE-2018-7804 — Medium (CVSS 6.1): A URL Redirection to Untrusted Site vulnerability exists in the embedded web servers in all Modicon M340, Premium,…

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