CVE-2026-28318

SolarWinds Serv-U Unauthenticated Denial of Service Vulnerability

High 7.5
Exploited: added to CISA KEV 5 Jun 2026

Description

SolarWinds Serv-U is susceptible to specially crafted POST requests that crash the Serv-U service without authentication using Content-Encoding: deflate. Mitigation steps are provided to secure customer environments in the SolarWinds Trust Center if you are unable to deploy the update

Key facts

Published: 4 Jun 2026
Last changed: 21 Oct 2026
Assigned by: SolarWinds
KEV added: 5 Jun 2026
KEV fix due: 19 Jun 2026
EPSS: 87.267% likely to be exploited in the next 30 days, higher than 99.756% of CVEs (scores for 15 Nov 2026)
SSVC (CISA): Exploitation: active; Automatable: yes; Technical impact: partial

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

7.5CVSS 3.1, Highfrom the CNA (SolarWinds)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What to do

Upgrade to SolarWinds Serv-U 15.5.4 Hotfix 1. Use the mitigation steps until the upgrade is possible.CNA solution statement
Block any POST requests containing 'Content-Encoding: deflate'. This function is not required for SolarWinds Serv-U.CNA workaround statement
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.CISA KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

CAPEC-469 HTTP DoS (CNA impact statement)

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Vendor	Product	Versions
SolarWinds	Serv-U	Default status: unaffected 0 up to and including 15.5.4 (affected)