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

Exploited in the wild Critical 9.8 Published 23 Sep 2025 Updated 4 Aug 2026

Unauthenticated attackers can achieve remote code execution and privilege escalation via deserialization in SolarWinds Web Help Desk.

Exploited in the wild: Since 9 Mar 2026
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-26399?

CVE-2025-26399 is a critical unsafe deserialization vulnerability in SolarWinds Web Help Desk, published on 23 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-502

Which versions are affected by CVE-2025-26399?

It affects 1 product.

Products include Solarwinds Web Help Desk.

How do I fix CVE-2025-26399?

No fix has been published for CVE-2025-26399 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 12 Mar 2026.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2025-26399 being exploited?

Yes. Attackers have exploited CVE-2025-26399 in the wild since at least 9 Mar 2026, including in ransomware campaigns.

Public exploit code: 1 Nuclei template and 1 proofs of concept on GitHub.

Sources

Also known as GHSA-vfrj-f292-3f24.