CVE-2014-3931
Multi-Router Looking Glass (MRLG) Buffer Overflow Vulnerability
Looking Glass Multi-Router Looking Glass (MRLG)
fastping.c in MRLG (aka Multi-Router Looking Glass) before 5.5.0 allows remote attackers to cause an arbitrary memory write and memory corruption.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 7 July 2025. US federal agencies were required to remediate it by 28 July 2025.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 29%, which is higher than 98.1% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2014-3931 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2014-3931.
What does CVE-2014-3931 affect?
CVE-2014-3931 affects Looking Glass Multi-Router Looking Glass (MRLG). fastping.c in MRLG (aka Multi-Router Looking Glass) before 5.5.0 allows remote attackers to cause an arbitrary memory write and memory corruption.
How severe is CVE-2014-3931?
CVE-2014-3931 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 29%, higher than 98.1% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 28 July 2025.
How should organisations respond to CVE-2014-3931?
Apply the vendor patch for Looking Glass Multi-Router Looking Glass (MRLG) as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.