CVE-2026-28318
CVE-2026-28318 is a security flaw in SolarWinds Serv-U, SolarWinds’ IT management software. Attackers can crash SolarWinds Serv-U or stop it working from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 5 Jun 2026.[1]
SolarWinds Serv-U is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. SolarWinds has published a fix or advice.
Description
CISA calls it an uncontrolled resource consumption in SolarWinds Serv-U. In its words: “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.”[1]
The CVE record adds: “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”[2]
The underlying weakness is resource exhaustion (CWE-400), in MITRE’s list of common software weaknesses.
It scores 7.5 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; SolarWinds’s advisory has them[3]. CISA names the product as SolarWinds Serv-U.
Most families won’t have SolarWinds Serv-U; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 5 Jun 2026, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 19 Jun 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 44%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
SolarWinds has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.SolarWinds Serv-U is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 19 Jun 2026 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.5.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 44%.[4] |
See also
Other SolarWinds Serv-U flaws
- CVE-2024-28995: path traversal ·
- CVE-2021-35247: improper input validation ·
- CVE-2021-35211: remote code execution ·
Other SolarWinds flaws
- CVE-2025-26399, SolarWinds Web Help Desk: deserialization of untrusted data ·
- CVE-2025-40536, SolarWinds Web Help Desk: security control bypass ·
- CVE-2025-40551, SolarWinds Web Help Desk: deserialization of untrusted data ·
- CVE-2024-28987, SolarWinds Web Help Desk: hardcoded credential ·
- CVE-2024-28986, SolarWinds Web Help Desk: deserialization of untrusted data ·
Other resource exhaustion flaws
- CVE-2026-45498, Microsoft Defender: denial of service ·
- CVE-2023-44487, IETF HTTP/2: rapid reset attack ·
- CVE-2023-38180, Microsoft .NET Core and Visual Studio: denial-of-service ·
- CVE-2004-1464, Cisco IOS: denial-of-service ·
- CVE-2020-3569, Cisco IOS XR: software DVMRP memory exhaustion ·
Every SolarWinds flaw on CISA’s list · Everything added in June 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “SolarWinds Serv-U Uncontrolled Resource Consumption Vulnerability”. Known Exploited Vulnerabilities Catalog, added 5 Jun 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-28318 Detail”. National Vulnerability Database, published 4 Jun 2026.
- ^ SolarWinds. Advisories and fixes: solarwinds.com, documentation.solarwinds.com, documentation.solarwinds.com, solarwinds.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.437, percentile 98.7, 31 Oct 2026.
- CVE Program. “CVE-2026-28318”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.