CVE-2026-28318SolarWinds Serv-U Unauthenticated Denial of Service Vulnerability
- 7.5HighCVSS base score
- 48.0%Exploitation in 30 daysEPSS · top 1.1% of all CVEs
- YesKnown exploitedin CISA's KEV since 5 Jun 2026
- YesPublic exploitsa reference or SSVC says so
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
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as SolarWinds Serv-U Uncontrolled Resource Consumption Vulnerability.
- Added
- 5 Jun 2026
- Fix due (US federal)
- 19 Jun 2026
- Used by ransomware
- Not known
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 5 Jun 2026.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By SolarWinds
- 3 months later
· 3 months later
Published
- 1 day later
· 1 day later
Added to CISA KEV
Known exploited in the wild
- 5 months later
· 5 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| SolarWindsCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 48.0% · top 1.1% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- affected ≤ 15.5.4
What to do
Solution: Upgrade to SolarWinds Serv-U 15.5.4 Hotfix 1. Use the mitigation steps until the upgrade is possible.
Workaround: Block any POST requests containing 'Content-Encoding: deflate'. This function is not required for SolarWinds Serv-U.
References
References3
- https://www.solarwinds.com/trust-center/security-advisories/CVE-2026-28318 (opens in a new tab)
- https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-5-4-hotfix-1_release_notes.htm (opens in a new tab)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-28318 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-34268 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-28318)Record last updated .