CVE-2025-40539

Solarwinds Serv-U ≤ 15.5.4

Published

24 February 2026

Modified

24 February 2026

Patch / advisory

View advisory

CVSS Score v3.1 9.1

Click a component to see what it means

Raw vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS Score 0.0044 37th percentile

Risk Priority 58 floored blend · peak EPSS

Summary

CVE-2025-40539 is a critical-severity Incorrect Type Conversion or Cast (CWE-704) vulnerability in Solarwinds Serv-U. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 37th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-40539 is a type confusion vulnerability (CWE-704) in SolarWinds Serv-U, a file transfer server software. When exploited, it enables a malicious actor to execute arbitrary native code with the privileges of the affected account. The vulnerability carries a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H), reflecting its high impact despite requiring high privileges, due to the scope change from network-accessible exploitation.

Exploitation requires administrative privileges on the target system (PR:H), limiting it to attackers who have already gained such access, such as compromised insiders or those escalating from lower privileges. A successful attack can be performed remotely over the network with low complexity (AV:N/AC:L), achieving complete confidentiality, integrity, and availability impacts (C:H/I:H/A:H) in a changed scope (S:C), effectively allowing full system compromise under the service's privileged context.

SolarWinds has addressed the issue in Serv-U version 15.5.4, as detailed in the release notes at https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-5-4_release_notes.htm. Additional mitigation guidance and details are provided in the vendor's security advisory at https://www.solarwinds.com/trust-center/security-advisories/CVE-2025-40539. On Windows deployments, the risk is considered medium because Serv-U services often run under less-privileged accounts by default.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2025-207545

Vulnerability Data

A type confusion vulnerability exists in Serv-U which when exploited, gives a malicious actor the ability to execute arbitrary native code as privileged account. This issue requires administrative privileges to abuse. On Windows deployments, the risk is scored as a…

medium because services frequently run under less-privileged service accounts by default.

CWE(s): CWE-704

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1212 Exploitation for Credential Access Credential Access

Adversaries may exploit software vulnerabilities in an attempt to collect credentials.

attack.mitre.org →

T1687 Exploitation for Defense Impairment Defense Impairment

Adversaries may exploit vulnerabilities in security software, infrastructure, or defensive components to degrade, disable, or otherwise continue to impair their ability to prevent, detect, or respond to malicious activity.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-40540Same product: Solarwinds Serv-U

CVE-2025-40541Same product: Solarwinds Serv-U

CVE-2021-35211Same product: Solarwinds Serv-U

CVE-2021-35247Same product: Solarwinds Serv-U

CVE-2023-40053Same product: Solarwinds Serv-U

CVE-2026-28310Same product: Solarwinds Serv-U

CVE-2026-28309Same product: Solarwinds Serv-U

CVE-2025-40547Same product: Solarwinds Serv-U

CVE-2024-28073Same product: Solarwinds Serv-U

CVE-2024-45711Same product: Solarwinds Serv-U

Affected Assets

solarwinds

serv-u

≤ 15.5.4

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds incorrect type conversions or casts.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented development standards and tools can mandate safe typing, casting rules, and compiler checks that stop the weakness from being introduced.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles can require type-safe design and casting practices that structurally avoid incorrect conversions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match

prevents

Secure SDLC practices directly prevent type-conversion flaws via coding standards, reviews, and testing.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match

finds

Security testing can uncover type-conversion defects before release.

A.8.25 Secure development life cycle partial match

prevents

Secure development lifecycle includes type-safety reviews that reduce incorrect casts.

A.8.26 Application security requirements partial match

prevents

Application security requirements can mandate strong typing and safe casting rules.

A.8.27 Secure system architecture and engineering principles partial match

degrades

Secure architecture principles discourage unsafe type conversions in design.