9.8

CVE-2025-26399: SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability

CVSS: 9.8v3.1CriticalKEVRansomwareAnalyzed
Published 23-09-2025Last modified 04-08-2026
Open JSON

Vulnerability summary

CVE-2025-26399 is a critical (CVSS 9.8) Deserialization of Untrusted Data vulnerability in SolarWinds Web Help Desk. It is known to be exploited: CISA lists it, first on 09-03-2026. It has been used in ransomware campaigns. EPSS estimates a 90.12% chance of exploitation in the next 30 days, higher than 99.7% of scored vulnerabilities.

Overall risk
90/100
0100
Critical · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
90.12%
0%100%
Critical · +0.62 pp in 30 days
KEVListedCISA
RansomwareKnown useFlagged by CISA
Public exploits0No public exploits recorded

Timeline

  1. 23-09-2025
    PublishedVulnerability first disclosed.
  2. 09-03-2026
    Added to CISA KEVSolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability
  3. 12-03-2026
    CISA remediation dueApply mitigations per vendor instructions.
  4. 04-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

90.12%

Chance of exploitation in the next 30 days

Percentile

100%

Versus all other CVEs

30-day change

+0.62 pp

From 89.50% on 17-09-2026

17-09-202617-10-2026
EPSS score
90.12%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
09-03-2026
Federal due date
12-03-2026
Ransomware

CISA required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. www.solarwinds.com/trust-center/security-advisories/cve-2025-26399 documentation.solarwinds.com/en/… nvd.nist.gov/vuln/detail/CVE-2025-26399

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Solarwinds1 product
  • web_help_desk12.8.7 and below | ≤ 12.8.6 | 12.8.7

1 vendor · 1 product

References

4 links