CVE-2025-26399 — Web Help Desk
CRITICALCVE-2025-26399 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in solarwinds web help desk. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-03-09) and has been used in ransomware campaigns — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
SolarWinds Web Help Desk was found to be susceptible to an unauthenticated AjaxProxy deserialization remote code execution vulnerability that, if exploited, would allow an attacker…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-03-09 — including use in ransomware campaigns. Federal agencies were required to remediate by 2026-03-12.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2025-26399.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2025-26399 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
SolarWinds Web Help Desk was found to be susceptible to an unauthenticated AjaxProxy deserialization remote code execution vulnerability that, if exploited, would allow an attacker to run commands on the host machine. This vulnerability is a patch bypass of CVE-2024-28988, which in turn is a patch bypass of CVE-2024-28986.
Affected Products
web help desksolarwindsDetection & mitigation playbook
Vendor / applianceDetect
Inventory every solarwinds web help desk deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2025-26399 yet — track the solarwinds web help desk advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
How to detect CVE-2025-26399
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2025-26399 -u https://target- Template
- SolarWinds Web Help Desk < 12.8.7 - AjaxProxy Deserialization RCE
- Severity
- critical
- Impact
- Attackers can execute arbitrary commands on the host machine remotely without authentication, leading to full system compromise.
- Remediation
- Update to the latest version that addresses this vulnerability.
Template by ProjectDiscovery nuclei-templates (popy21), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2025-26399 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.