CVE-2026-28318: SolarWinds Serv-U Uncontrolled Resource Consumption Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 5 Jun 2026, 1 day after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 43.7%
EPSS score, percentile 98.7 of all scored records
- How severe?
- 7.5 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline 19 Jun 2026. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 15.5.4 and earlier
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
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 due date for this action: 19 June 2026.
Solution (from the CVE record)
Upgrade to SolarWinds Serv-U 15.5.4 Hotfix 1. Use the mitigation steps until the upgrade is possible.
Workaround (from the CVE record)
Block any POST requests containing 'Content-Encoding: deflate'. This function is not required for SolarWinds Serv-U.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://www.solarwinds.com/trust-center/security-advisories/cve-2026-28318
- https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-5-4-hotfix-1_release_notes.htm#link7
- https://nvd.nist.gov/vuln/detail/CVE-2026-28318
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 15.5.4 and earlier |
Versions not listed are: unaffected.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this 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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2026-28318 to its Known Exploited Vulnerabilities (KEV) catalog on 5 Jun 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 19 Jun 2026.
- The CVE record was published on 4 Jun 2026, 1 day before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 7.5 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 43.7% (percentile 98.7), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
SolarWinds Serv-U Unauthenticated Denial of Service Vulnerability
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
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-400: Uncontrolled Resource Consumption
Attack patterns (CAPEC)
- CAPEC-469: HTTP DoS
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 4 Jun 2026 | CVE record published |
| 5 Jun 2026 | Added to CISA KEV |
| 19 Jun 2026 | CISA due date for the required action |
| 21 Oct 2026 | CVE record last updated |
References
More exploited SolarWinds vulnerabilities
- CVE-2025-26399: SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability
- CVE-2025-40536: SolarWinds Web Help Desk Security Control Bypass Vulnerability
- CVE-2025-40551: SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability
- CVE-2024-28987: SolarWinds Web Help Desk Hardcoded Credential Vulnerability
- CVE-2024-28986: SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability
- CVE-2024-28995: SolarWinds Serv-U Path Traversal Vulnerability