The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has officially included a SolarWinds Serv-U vulnerability in its Known Exploited Vulnerabilities (KEV) catalog. The issue, identified as CVE-2026-28318 and assigned a CVSS v3.1 score of 7.5, impacts SolarWinds Serv-U, a managed file transfer (MFT) and secure file server solution developed by SolarWinds.
CVE-2026-28318 is classified as an unauthenticated denial-of-service (DoS) vulnerability. It allows a remote attacker to crash the Serv-U service by sending a specially crafted HTTP POST request containing a Content-Encoding: deflate header. Notably, the attack does not require authentication, making exploitation relatively straightforward.
If successfully exploited, this vulnerability can interrupt file transfer services and render the platform inaccessible to legitimate users, potentially affecting business operations. In response, SolarWinds has released security updates to remediate the flaw and strongly advises organizations to apply the patches without delay. For environments where immediate patching is not feasible, the SolarWinds Trust Center provides temporary mitigation options.
According to the official advisory, Serv-U can be forced to crash through maliciously crafted POST requests that leverage the Content-Encoding: deflate header, even in the absence of valid credentials.
The vulnerability affects Serv-U version 15.5.4 and earlier releases. The issue has been resolved in Serv-U version 15.5.4 Hotfix 1 (HF1).
Under Binding Operational Directive (BOD) 22-01, which focuses on reducing risks associated with known exploited vulnerabilities, Federal Civilian Executive Branch (FCEB) agencies are required to remediate cataloged vulnerabilities by specified deadlines to safeguard their networks from active threats. Security professionals also strongly advise private-sector organizations to review the KEV catalog regularly and remediate any applicable vulnerabilities within their environments.
CISA has set a deadline of June 19, 2026, for federal agencies to address this specific vulnerability.
Found this article interesting? Follow us on X(Twitter) ,Threads and FaceBook to read more exclusive content we post.
