What products are affected by CVE-2025-26399?

CVE-2025-26399 affects SolarWinds Web Help Desk. Refer to the vendor advisory and NVD record for affected versions.

Is there a public exploit for CVE-2025-26399?

Yes. Public exploit code or proof-of-concept has been identified for CVE-2025-26399. This lowers the barrier for exploitation and increases the urgency of patching. Organizations should prioritize remediation immediately.

What is the EPSS score for CVE-2025-26399?

CVE-2025-26399 has an EPSS score of 26.7%, placing it in the 96th percentile. This means it has a 26.7% probability of being exploited in the next 30 days, higher than 96% of all known vulnerabilities. EPSS (Exploit Prediction Scoring System) is maintained by FIRST and uses real-world threat data to estimate exploitation likelihood.

Actively Exploited — CISA KEV

CVE-2025-26399: SolarWinds Web Help Desk Critical Vulnerability

Severity: Critical | CVSS 3.1: 9.8 | Published: 2025-09-23 | KEV Added: 2026-03-09

What is CVE-2025-26399?

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.

Technical Analysis

Weakness Classification

This vulnerability is classified as CWE-502 — Deserialization of Untrusted Data. The application deserializes untrusted data without sufficient validation, which can lead to remote code execution, denial of service, or other attacks.

Attack Vector Breakdown

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Impact Analysis

This vulnerability is exploitable over the network, meaning any system reachable via the internet or internal network is potentially at risk without physical access. The attack complexity is low, requires no special privileges, and needs no user interaction — making it straightforward to exploit at scale. Successful exploitation can result in full confidentiality breach (complete data disclosure), complete integrity compromise (data modification or code execution), total availability loss (denial of service). The application deserializes untrusted data without sufficient validation, which can lead to remote code execution, denial of service, or other attacks.

Exploitation Probability (EPSS): 26.7% chance of exploitation in the next 30 days (96th percentile). This is a significantly elevated exploitation probability — prioritize patching.

Exploit Availability

Public exploit code or proof-of-concept is available for CVE-2025-26399. This significantly increases the risk of exploitation, as attackers can use or adapt existing exploit code rather than developing their own. A public exploit reference has been identified. Organizations should treat this as an urgent patching priority.

Is CVE-2025-26399 being exploited?

Yes. CVE-2025-26399 is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, restricted to CVEs with confirmed active exploitation in the wild. CISA added this vulnerability on 2026-03-09. Inclusion in KEV triggers the patching mandate under BOD 22-01 for U.S. federal civilian agencies, with a remediation deadline of 2026-03-12. Additionally, public exploit code is available, which lowers the barrier for attackers.

How to fix CVE-2025-26399

Apply the security update issued by SolarWinds for Web Help Desk. If an immediate patch is not possible, consult the vendor advisory for mitigation guidance, restrict network exposure of the affected service, and monitor logs for indicators of exploitation. CISA's Known Exploited Vulnerabilities catalog requires U.S. federal agencies to remediate this vulnerability by the due date shown below under Binding Operational Directive 22-01. Private organizations should treat KEV entries as priority-one patches because active exploitation has been confirmed in the wild.

Related Vulnerabilities

Other actively exploited vulnerabilities affecting Web Help Desk or sharing the same weakness (CWE-502):

CVE-2025-40551 (Critical 9.8) [same product + same CWE] — SolarWinds Web Help Desk was found to be susceptible to an untrusted data…
CVE-2025-40536 (High 8.1) [same product] — SolarWinds Web Help Desk was found to be susceptible to a security control…
CVE-2026-28318 (High 7.5) [same vendor] — SolarWinds Serv-U is susceptible to specially crafted POST requests that crash…
CVE-2026-45247 (Critical 9.8) [same CWE] — Mirasvit Full Page Cache Warmer for Magento 2 before version 1.11.12 contains…
CVE-2023-21529 (High 8.8) [same CWE] — Microsoft Exchange Server Remote Code Execution Vulnerability

Frequently asked questions

Is CVE-2025-26399 critical?

CVE-2025-26399 has a CVSS 3.1 base score of 9.8 — Critical severity. It should be treated as a priority patch, especially given the active exploitation confirmed by CISA. The availability of public exploit code further increases the urgency.

Is CVE-2025-26399 being actively exploited?

Yes — CISA added CVE-2025-26399 to the Known Exploited Vulnerabilities catalog on 2026-03-09. Inclusion in KEV means CISA has confirmed in-the-wild exploitation. Public exploit code has also been identified, making exploitation accessible to a broader range of threat actors.

How do I patch CVE-2025-26399?

Apply the security update from SolarWinds for Web Help Desk. Federal agencies must remediate by 2026-03-12 under BOD 22-01.

What type of vulnerability is CVE-2025-26399?

CVE-2025-26399 is classified under CWE-502 (Deserialization of Untrusted Data). The application deserializes untrusted data without sufficient validation, which can lead to remote code execution, denial of service, or other attacks.

What is the CVSS score for CVE-2025-26399?

CVE-2025-26399 has a CVSS 3.1 base score of 9.8, classifying it as Critical severity. The attack vector is Network, attack complexity is Low, and no privileges are required.