CVE-2026-28318: SolarWinds Serv-U denial of service via crafted POST request

CVE-2026-28318 · Severity: critical · CVSS 7.5 · Exploited in the wild · Published 2026-06-04

SolarWinds Serv-U, a widely used file transfer solution, is vulnerable to a denial-of-service attack that can crash the service. An unauthenticated attacker can send a specially crafted web request that exhausts system resources, making the file transfer server unavailable to legitimate users. This can disrupt business operations and automated data exchange processes until the service is manually restarted or patched.

Technologies: SolarWinds Serv-U. Vendors: SolarWinds.

Quick answers

Is CVE-2026-28318 exploited in the wild?
Yes. CVE-2026-28318 is known to be exploited in the wild, first recorded on 5 June 2026. Treat it as urgent.
How severe is CVE-2026-28318?
Critical severity, with a CVSS score of 7.5, published 4 June 2026.
Which products and versions are affected?
SolarWinds Serv-U Prior to 15.4.2 Hotfix 1, Prior to 15.5.4 Hotfix 1.
Is there a fix for CVE-2026-28318?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-28318 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-28318?
Check whether you run SolarWinds Serv-U at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A denial-of-service vulnerability exists in SolarWinds Serv-U due to improper handling of compressed data in HTTP POST requests. The flaw is categorized as CWE-400 (Uncontrolled Resource Consumption) and is triggered when the service processes a request containing a 'Content-Encoding: deflate' header. An unauthenticated remote attacker can exploit this by sending a malicious payload that causes the service to crash. This vulnerability has been reported as exploited in the wild. SolarWinds has released Serv-U 15.4.2 Hotfix 1 to address the issue, and mitigation steps are available for environments where immediate patching is not feasible.

Affected products

  • SolarWinds Serv-U Prior to 15.4.2 Hotfix 1

Timeline

  • 2026-06-04: disclosed
  • 2026-06-04: advisory
  • 2026-06-04: exploited: Reported as exploited in the wild in advisory metadata.

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