SolarWinds Web Help Desk Remote Command Execution (CVE-2025-26399)

Historical catalog analysis: CISA added this entry on March 09, 2026. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-26399 is a vulnerability involving the deserialization of untrusted data (CWE-502) within the AjaxProxy component of SolarWinds Web Help Desk. This flaw could allow an attacker to execute arbitrary commands on the host machine where the software is running. The vulnerability has been identified as having known use in ransomware campaigns.

Exposure and applicability

This vulnerability affects organizations deploying SolarWinds Web Help Desk. Because the flaw resides in a component that handles data processing (AjaxProxy), any instance of the product that has not applied the vendor’s specific mitigations is potentially exposed to remote command execution. Infrastructure owners should prioritize assets based on their network visibility and the level of privilege assigned to the service account running the Web Help Desk application.

Remediation priorities

Based on the reported exploitation by ransomware actors, we analyze the following priority actions for vulnerability management teams:

1. Immediate Mitigation Application: Apply vendor-provided mitigations or updates as specified in the SolarWinds security advisories. For those utilizing cloud services, follow applicable BOD 22-01 guidance.
2. Asset Decommissioning: In scenarios where mitigations are unavailable or cannot be verified, we recommend discontinuing use of the product to eliminate the attack surface.
3. Privilege Review: While not a direct fix for the deserialization flaw, reducing the permissions of the account running the Web Help Desk service could limit the impact of successful command execution on the host machine.

How to validate remediation

Verification must move beyond simple version checks, as a deployed update does not inherently guarantee that the vulnerability is neutralized in the active environment. We recommend the following validation approach:

• Configuration Audit: Verify that the specific hotfix or mitigation identified by the vendor is active and correctly configured across all instances.
• Behavioral Validation: In a staged environment, security teams should verify that the AjaxProxy component no longer accepts the untrusted data patterns associated with this deserialization flaw.
• Deployment Confirmation: Cross-reference installed build numbers against the vendor’s fixed version list to ensure no legacy or shadow instances remain unpatched.

Limits and open questions

Applying a patch or mitigation could reduce the likelihood of exploitation, but it does not eliminate all residual risk associated with the host machine if previous compromise has already occurred. It remains unclear from the available data exactly which versions are affected beyond those addressed by the hotfixes. Furthermore, because this is a deserialization flaw, defenders should consider whether other components within the same environment share similar data-handling patterns that may not yet be cataloged as vulnerabilities.

Source and editorial note

CVE-2025-26399: SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability · Source date: March 09, 2026 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: March 12, 2026. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: September 18, 2026 at 00:57 UTC.

Request a Vulnerability Assessment