CVE-2018-9276
CVE-2018-9276 is a security flaw in Paessler PRTG Network Monitor. Attackers can run commands on Paessler PRTG Network Monitor. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 4 Feb 2025.[1]
Paessler PRTG Network Monitor 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. Paessler has published a fix or advice.
Description
CISA calls it an OS command injection in Paessler PRTG Network Monitor. In its words: “Paessler PRTG Network Monitor contains an OS command injection vulnerability that allows an attacker with administrative privileges to execute commands via the PRTG System Administrator web console.”[1]
The CVE record adds: “An issue was discovered in PRTG Network Monitor before 18.2.39. An attacker who has access to the PRTG System Administrator web console with administrative privileges can exploit an OS command injection vulnerability (both on the server and on devices) by sending malformed parameters in sensor or notification management scenarios.”[2]
The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.
It scores 7.2 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Paessler’s advisory has them[3]. CISA names the product as Paessler PRTG Network Monitor.
Most families won’t have Paessler PRTG Network Monitor; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 4 Feb 2025, 2,409 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 25 Feb 2025 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 87%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Paessler has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Paessler PRTG Network Monitor 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 25 Feb 2025 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 7.2.[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 87%.[4] |
See also
Other Paessler PRTG Network Monitor flaws
- CVE-2018-19410: local file inclusion ·
Other OS command injection flaws
- CVE-2026-110447, Collabora Online – Built-in CODE Server: online – built-in CODE server OS command injection ·
- CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
- CVE-2026-83549, SonicWall SMA1000 Appliances: OS command injection ·
- CVE-2026-49869, Kestra OSS: OSS OS command injection ·
- CVE-2026-73570, Synacor Zimbra Collaboration Suite (ZCS): OS command injection ·
Added the same day
- CVE-2024-45195, Apache OFBiz: forced browsing ·
- CVE-2024-29059, Microsoft .NET Framework: information disclosure ·
- CVE-2018-19410, Paessler PRTG Network Monitor: local file inclusion ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Paessler PRTG Network Monitor OS Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 4 Feb 2025.
- ^ National Institute of Standards and Technology. “CVE-2018-9276 Detail”. National Vulnerability Database, published 2 Jul 2018.
- ^ Paessler. Advisories and fixes: paessler.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.870, percentile 99.7, 31 Oct 2026.
- CVE Program. “CVE-2018-9276”. 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.