SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability
SolarWinds Web Help Desk contain a deserialization of untrusted data vulnerability in AjaxProxy that could allow an attacker to run commands on the host machine.
- Vendor
- SolarWinds
- Product
- Web Help Desk
- CVSS
- 9.8
- EPSS (exploit probability)
- 90.1%
- Status
- kevransomware use
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2025-26399 being exploited?
Yes. CISA added CVE-2025-26399 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild. CISA marks it as known to be used in ransomware campaigns.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 90.1% (scored October 17, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-21. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
US federal civilian agencies must remediate by (3 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other SolarWinds Web Help Desk CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2025-40536 SolarWinds Web Help Desk Security Control Bypass Vulnerability | [ HIGH ] | 8.1 | 73.6% | |
| CVE-2025-40551 SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability | [ CRITICAL ] | 9.8 | 84.2% | |
| CVE-2024-28987 SolarWinds Web Help Desk Hardcoded Credential Vulnerability | [ CRITICAL ] | 9.1 | 93.3% | |
| CVE-2024-28986 SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability | [ CRITICAL ] | 9.8 | 84.6% |