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Broken Access Control in SolarWinds Serv-U
CVE-2026-28321 is a critical broken access control vulnerability in SolarWinds Serv-U affecting version 15.5.4 HF1 and earlier on Windows and Linux. Weak access checks allow an authenticated attacker with domain administrator privileges to perform arbitrary file read and write operations within the affected Serv-U environment. This unauthorized file access can then be leveraged to escalate privileges further and, particularly on Linux deployments, achieve code execution with root privileges. The issue is classified as broken access control and has been associated with high impact to confidentiality, integrity, and availability.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation can give a privileged attacker unauthorized access to read and modify arbitrary files, undermining both confidentiality and integrity of the affected system. This access can be used to escalate privileges and ultimately execute code as root, especially on Linux systems, resulting in full system compromise. The impact on Windows installations is described as lower, but unauthorized file access and privilege escalation risk remain significant.
If you can’t patch tonight, do this now.
If immediate patching is not possible, restrict domain administrator and other high-privilege access to Serv-U, minimize exposure of administrative functionality, and avoid exposing Serv-U instances to the public internet where possible. Review and tighten Serv-U rights and permission assignments to reduce the likelihood of abuse by already-privileged users.
Patch, then assume compromise.
Upgrade SolarWinds Serv-U to version 2026.3 or later, which includes the vendor fix for CVE-2026-28321. Older affected releases, including 15.5.4 HF1 and earlier, should be considered vulnerable and updated immediately.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.