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Actively exploited

CVE-2026-28318 SolarWinds Serv-U Uncontrolled Resource Consumption Vulnerability

SolarWinds Serv-U contains an uncontrolled resource consumption vulnerability that allows specially crafted POST requests using the Content-Encoding: deflate header to crash the Serv-U service without authentication.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 5 Jun 2026.
  • Rated High severity (CVSS 7.5, scored by Vendor).
  • It has been in the catalogue for 154 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

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

Affected Versions

ProductVersions
SolarWinds Serv-U15.5.4 and earlier

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for SolarWinds Serv-U. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 19 Jun 2026 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited SolarWinds Flaws

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CVE-2025-26399 · RansomwareSolarWinds Web Help Desk Deserialization of Untrusted Data VulnerabilityAdded 9 Mar 2026CVE-2025-40536SolarWinds Web Help Desk Security Control Bypass VulnerabilityAdded 12 Feb 2026CVE-2025-40551SolarWinds Web Help Desk Deserialization of Untrusted Data VulnerabilityAdded 3 Feb 2026CVE-2024-28987SolarWinds Web Help Desk Hardcoded Credential VulnerabilityAdded 15 Oct 2024CVE-2024-28986SolarWinds Web Help Desk Deserialization of Untrusted Data VulnerabilityAdded 15 Aug 2024CVE-2024-28995SolarWinds Serv-U Path Traversal Vulnerability Added 17 Jul 2024

All 11 exploited SolarWinds vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2026-28318 and every other exploited flaw on the list.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2026-28318
  3. CVE record: CVE-2026-28318
  4. FIRST EPSS
  5. solarwinds.com/trust-center/security-advisories/cve-2026-28318
  6. documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-5-4-hotfix-1_rel
  7. solarwinds.com/trust-center/security-advisories/CVE-2026-28318
  8. documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-5-4-hotfix-1_rel