Security readout for executives and security teams
Plain-English summary
This is a critical SolarWinds Web Help Desk flaw that can let an unauthenticated attacker run commands on the server. It affects versions 12.8.7 and below and is listed by CISA as known exploited. Treat exposed Web Help Desk systems as urgent business risk.
Executive priority
Immediate action is warranted. This is a critical, unauthenticated server-side issue in an enterprise support platform, with known exploitation cited by CISA. Prioritize patching, exposure reduction, and compromise checks.
Technical view
CVE-2025-26399 is a CWE-502 unsafe deserialization issue in the Web Help Desk AjaxProxy component. The CVSS 3.1 score is 9.8. It is described as a patch bypass for CVE-2024-28988, which bypassed CVE-2024-28986, and can allow remote code execution on the host.
Likely exposure
Organizations running SolarWinds Web Help Desk 12.8.7 or earlier are in scope. Internet-facing or broadly reachable deployments carry the highest risk because exploitation is unauthenticated, network-based, low complexity, and requires no user interaction.
Exploitation context
Active exploitation is supported by CISA KEV listing and a Microsoft advisory referenced in the source bundle. The provided sources do not include exploit payloads, and none are needed to assess urgency.
Researcher notes
Focus on asset discovery, version and hotfix validation, and detection around AjaxProxy requests and host-level execution artifacts. The source bundle confirms the patch-bypass lineage but does not provide IOCs or detailed exploitation mechanics.
Mitigation direction
- Identify all SolarWinds Web Help Desk instances and versions.
- Apply SolarWinds guidance, including the 12.8.7 Hotfix 1 release where applicable.
- Restrict Web Help Desk access to trusted networks until patched.
- Review related prior fixes for CVE-2024-28988 and CVE-2024-28986.
- Follow CISA KEV direction for remediation timelines.
Validation and detection
- Confirm each instance is not version 12.8.7 or below without the hotfix.
- Verify the SolarWinds hotfix is installed successfully.
- Check whether Web Help Desk is internet-accessible.
- Review logs for suspicious AjaxProxy activity.
- Inspect hosts for unexpected command execution or new persistence indicators.
Public sources used
Michael Williams reviewed this cited source version on .
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2025-26399 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.solarwinds.com/trust-center/security-advisories/CVE-2025-26399CVE reference
- https://documentation.solarwinds.com/en/success_center/whd/content/release_notes/whd_12-8-7-hotfix-1_release_notes.htmCVE reference
- https://www.microsoft.com/en-us/security/blog/2026/02/06/active-exploitation-solarwinds-web-help-desk/CVE reference · third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-26399CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.