Critical RCE and Authentication Bypass Vulnerabilities in SolarWinds Web Help Desk
SolarWinds released security updates for Web Help Desk (WHD) to address multiple critical vulnerabilities that could allow unauthenticated remote attackers to bypass authentication and achieve remote code execution (RCE). The patched issues include two critical authentication bypass flaws, CVE-2025-40552 and CVE-2025-40554 (reported by watchTowr researcher Piotr Bazydlo), and two critical RCE flaws tied to untrusted data deserialization, CVE-2025-40553 (Bazydlo) and CVE-2025-40551 (reported by Horizon3.ai researcher Jimi Sebree), enabling remote command execution without prior access.
SolarWinds also fixed a high-severity hardcoded credentials issue, CVE-2025-40537, which could enable unauthorized access to administrative functions under certain conditions. The vendor advised administrators to upgrade to Web Help Desk 2026.1 and patch quickly, noting WHD has a history of being targeted and previously had vulnerabilities flagged as actively exploited by CISA, reinforcing the likelihood of rapid attacker interest following disclosure and patch availability.
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How this story unfolded
9 events from the most recent confirmed update back to the earliest known activity.
More than 170 exposed WHD instances reported still vulnerable
Researchers reported that over 170 internet-exposed SolarWinds Web Help Desk installations remained vulnerable to CVE-2025-40551 after active exploitation was confirmed, highlighting continued exposure despite available patches.
CISA sets February 6 deadline for federal remediation
Following the KEV addition, CISA set an urgent remediation deadline of February 6, 2026 for affected federal agencies and urged immediate patching or isolation of exposed systems.
CISA adds CVE-2025-40551 to KEV as actively exploited
CISA flagged SolarWinds Web Help Desk CVE-2025-40551 as actively exploited in attacks, added it to the Known Exploited Vulnerabilities catalog, and ordered U.S. federal civilian agencies to remediate under BOD 22-01.
Rapid7 releases detection coverage for critical WHD CVEs
Rapid7 said remote vulnerability checks for the four critical SolarWinds Web Help Desk CVEs were included in its January 28 content release for certain security products.
Researchers publicly disclose technical details for WHD exploit chain
Horizon3.ai and watchTowr publicly detailed how multiple Web Help Desk weaknesses could be chained to achieve unauthenticated remote code execution, including AjaxProxy/JSON-RPC deserialization paths, request-filter bypasses, static credentials, and indicators of compromise.
SolarWinds publishes advisory and patches six WHD vulnerabilities
SolarWinds released Web Help Desk 2026.1 and published a security advisory addressing six vulnerabilities affecting versions 12.8.8 Hotfix 1 and earlier, including four critical flaws for unauthenticated RCE and authentication bypass plus two high-severity issues involving access control bypass and hardcoded credentials.
SolarWinds provides a preview release for WHD fixes
As part of remediation efforts, SolarWinds issued a preview release containing fixes ahead of public availability of the final patched version.
SolarWinds confirms the reported WHD vulnerabilities
SolarWinds acknowledged and confirmed the reported Web Help Desk vulnerabilities during the coordinated disclosure process.
Researchers report SolarWinds WHD flaws to PSIRT
Horizon3.ai disclosed vulnerabilities in SolarWinds Web Help Desk to SolarWinds PSIRT, beginning the coordinated disclosure process for what became CVE-2025-40551 and related issues.
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Sources
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170+ SolarWinds Help Desk Installations Vulnerable to RCE Attacks Exposed Online
cybersecuritynews.com
Open sourceCISA Warns of SolarWinds Web Help Desk RCE Vulnerability Exploited in Attacks
cybersecuritynews.com
Open sourceCISA flags critical SolarWinds RCE flaw as exploited in attacks
bleepingcomputer.com
Open sourceSolarWinds Web Help Desk Critical Vulnerabilities: Unauthenticated RCE and Authentication Bypass Fixed in Emergency Patch
rescana.com
Open sourceCVE-2025-40551: SolarWinds WHD RCE | Horizon3.ai
horizon3.ai
Open sourceMultiple Critical SolarWinds Web Help Desk Vulnerabilities: CVE-2025-40551, CVE-2025-40552, CVE-2025-40553, CVE-2025-40554
rapid7.com
Open sourceSolarWinds warns of critical Web Help Desk RCE, auth bypass flaws
bleepingcomputer.com
Open sourceSolarWinds Web Help Desk Hit with Multiple RCE and Auth Bypass Vulnerabilities
securityonline.info
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CISA Orders Patching of Exploited SolarWinds Web Help Desk RCE (CVE-2025-40551)
The U.S. Cybersecurity and Infrastructure Security Agency (**CISA**) added **CVE-2025-40551**—a critical (CVSS 9.8) *SolarWinds Web Help Desk (WHD)* vulnerability—to its **Known Exploited Vulnerabilities (KEV)** catalog after confirming active exploitation. The flaw is described as **deserialization of untrusted data** that can enable **unauthenticated remote code execution**, potentially allowing full compromise of affected WHD servers; the issue was reported to SolarWinds by Horizon3.ai researcher **Jimi Sebree**. CISA also issued a directive requiring U.S. federal civilian agencies to patch CVE-2025-40551 by the stated deadline, and SolarWinds released a fix in *Web Help Desk* version **2026.1**. Reporting tied the bug to a prior WHD issue (**CVE-2024-28986**) and characterized CVE-2025-40551 as part of a sequence of vulnerabilities involving bypasses of earlier fixes; CISA’s KEV update also included additional exploited flaws in **Sangoma FreePBX** (including **CVE-2019-19006** and **CVE-2025-64328**) and **GitLab** (**CVE-2021-39935**, SSRF), expanding the set of vulnerabilities agencies must remediate under KEV timelines.
Jun 29, 2026
Active Exploitation of SolarWinds Web Help Desk Flaws Enables Remote Code Execution
SolarWinds warned that multiple vulnerabilities in **Web Help Desk** are being actively exploited, with reporting highlighting a critical flaw that can lead to **remote code execution** on exposed help-desk servers. Public references tie the activity to `CVE-2025-40554`, while additional SolarWinds advisories and third-party research point to related issues including `CVE-2025-40552`, `CVE-2025-40553`, and `CVE-2025-40536`, indicating a broader security problem affecting the product. Security researchers and defenders published proof-of-concept material and detection guidance shortly after disclosure, including a watchTowr repository focused on Web Help Desk exploitation and a GitHub Gist describing **uncommon process activity** associated with compromise. The combination of vendor advisories, media reporting, and public exploit research indicates that attackers moved quickly to weaponize the flaws, increasing risk for organizations that have not patched, isolated, or monitored SolarWinds Web Help Desk deployments.
Jul 1, 2026
Active Exploitation of SolarWinds Web Help Desk Insecure Deserialization (CVE-2025-26399)
**CVE-2025-26399** is a **critical insecure deserialization** flaw (CWE-502) in *SolarWinds Web Help Desk* that enables **unauthenticated remote code execution/command execution** over the network. The issue resides in the product’s **`AjaxProxy`** component, where untrusted serialized data can be processed without sufficient validation, allowing an attacker to deliver a crafted payload that results in arbitrary command execution on the host running the help desk application. Multiple reports indicate the vulnerability is **actively exploited in the wild**, prompting **CISA** to add CVE-2025-26399 to the **Known Exploited Vulnerabilities (KEV)** catalog. NetSPI notes the flaw was disclosed in 2025 and is described as a **patch bypass** related to earlier issues (**CVE-2024-28988** and **CVE-2024-28986**), and recommends immediate remediation by upgrading to **SolarWinds Web Help Desk 12.8.7 Hotfix 1 or later**; if patching is delayed, organizations should restrict network exposure of the server and increase monitoring for suspicious process execution and outbound connections.
Jun 29, 2026