CVE-2025-40551
SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability
SolarWinds Web Help Desk
SolarWinds Web Help Desk was found to be susceptible to an untrusted data deserialization vulnerability that could lead to remote code execution, which would allow an attacker to run commands on the host machine. This could be exploited without authentication.
Ransomware groups exploiting CVE-2025-40551
The Warlock ransomware and operator(s) are believed to be attributed to Storm-2603, a China-based threat actor who is also known to have deployed LockBit ransomware. There's also a crossover between victims with Black Basta. Both are RaaS and have a long list
Exploitation is attributed to these groups across their recorded activity. It does not follow that every organisation they listed was reached through CVE-2025-40551 — the source data does not record an entry point per incident.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 3 February 2026. US federal agencies were required to remediate it by 6 February 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 83.6%, which is higher than 99.7% 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
Recent listings by these groups
Disclosures from the groups above, newest first.
Frequently asked questions
Is CVE-2025-40551 being exploited by ransomware groups?
Yes. CVE-2025-40551 is recorded as exploited by Warlock. Between them these groups account for 78 victim disclosures in this database.
What does CVE-2025-40551 affect?
CVE-2025-40551 affects SolarWinds Web Help Desk. SolarWinds Web Help Desk was found to be susceptible to an untrusted data deserialization vulnerability that could lead to remote code execution, which would allow an attacker to run commands on the host machine. This could be exploited without authentication.
How severe is CVE-2025-40551?
CVE-2025-40551 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 83.6%, higher than 99.7% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 6 February 2026.
How should organisations respond to CVE-2025-40551?
Apply the vendor patch for SolarWinds Web Help Desk 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.