CVE-2025-26399: SolarWinds Web Help Desk exploited

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

What it is

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.

Description quoted from the CVE record (assigned by SolarWinds, published 2025-09-23).

Weakness: CWE-502: Deserialization of Untrusted Data

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since: 2026-03-09
US federal deadline: 2026-03-12
Ransomware use: Yes

Public exploit evidence (Exploit Observer)

Also known as: BDU:2025-11514, CNNVD-202509-3732, EUVD-2025-30842, GHSA-vfrj-f292-3f24, ZDI-25-906

VEDAS cluster: VEDAS:BELOWZERO

Exploit Observer links 6 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (6)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (3)

Research or write-up: https://watchtowr.com/rapidly-respond-to-cve-2025-26399
Research or write-up: https://www.huntress.com/blog/active-exploitation-solarwinds-web-help-desk-cve-2025-26399
Research or write-up: https://www.zerodayinitiative.com/advisories/ZDI-25-906

Vulnerability databases and vendor advisories (8)

Catalogue entries, not exploit evidence.

Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-30842
Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-vfrj-f292-3f24
Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-26399
Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-26399
Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202509-3732
Vulnerability database or vendor advisory: https://www.solarwinds.com/trust-center/security-advisories/CVE-2025-26399
Vulnerability database or vendor advisory: https://www.solarwinds.com/trust-center/security-advisories/cve-2025-26399
Vulnerability database or vendor advisory: https://www.tenable.com/cve/CVE-2025-26399

83 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS: 0.906
very likely to be attacked soon
VEDAS: 0.987
strong exploit evidence
On CISA KEV: Yes, since 2026-03-09
Detection rule: Nuclei · Suricata

EPSS (chance of attack)

VEDAS (exploit evidence)

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 64 days before CISA confirmed attacks.

Who is affected

Product	Affected	Not affected
SolarWinds Web Help Desk	version 12.8.7 and below	Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: solarwinds web_help_desk, solarwinds_inc. solarwinds_web_help_desk.

How to fix it

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.

Vendor guidance:

How to detect it

Nuclei template (active check)

Solarwinds - Insecure Deserialization
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.

Name and description quoted from the template, written by VEDAS.

The template sends 1 request (GET /helpdesk/WebObjects/Helpdesk.woa); it decides using dsl, regex matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash

nuclei -u https://your-host -t CVE-2025-26399.yaml

Show the template (51 lines)

yaml

id: CVE-2025-26399

info:
  name: "Solarwinds - Insecure Deserialization"
  author: vedas-arpsyndicate
  severity: critical
  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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2025-26399&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=solarwinds&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2025-26399
    cwe-id: CWE-502
  metadata:
    verified: false
  tags: cve,cve2025,solarwinds,webhelpdesk,deserialization,rce,kev,vkev,passive
http:
  - raw:
      - |
        GET /helpdesk/WebObjects/Helpdesk.woa HTTP/1.1
        Host: {{Hostname}}

    host-redirects: true
    max-redirects: 2

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains_any(body, "Web Help Desk Software", "SolarWinds WorldWide", "HCS Web Help Desk")'
          - 'compare_versions(version, "< 12.8.7")'
        condition: and

    extractors:
      - type: regex
        name: build_token
        part: body
        group: 1
        regex:
          - "\\?v=([0-9]+_[0-9]+_[0-9]+_[0-9]+)"
        internal: true

      - type: dsl
        name: version
        dsl:
          - 'replace(build_token, "_", ".")'

CVE-2025-26399.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2025-26399 Solarwinds - Insecure Deserialization. Add them to your Suricata rule set and reload.

Show the rules

suricata

alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2025-26399 Solarwinds - Insecure Deserialization"; flow:established,to_server; http.uri; content:"/helpdesk/WebObjects/Helpdesk.woa"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2025-26399; reference:url,https://www.exploit.observer/?keyword=CVE-2025-26399&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=solarwinds&match=exact; sid:1009210; rev:1;)

CVE-2025-26399.rules on GitHub

References

Exploits and technical analysis

https://www.microsoft.com/en-us/security/blog/2026/02/06/active-exploitation-solarwinds-web-help-desk/ (third-party-advisory)

Government sources

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-26399 (government-resource)

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.