CVE-2026-18577
CVE-2026-18577 is a security flaw in N-able N-central, remote-support software IT providers use to manage their customers’ computers. Attackers can get into N-able N-central without a valid password. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 3 Aug 2026.[1]
N-able N-central 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. N-able has published a fix or advice.
Description
CISA calls it an authentication bypass using an alternate path or channel in N-able N-central. In its words: “N-able N-central contains an authentication bypass using an alternate path or channel allows for authentication bypass and account takeover in N-central. This vulnerability is the result of an incomplete patch for CVE-2026-18556.”[1]
The underlying weakness is authentication bypass (CWE-288), in MITRE’s list of common software weaknesses.[2]
It scores 8.1 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; N-able’s advisory has them[3]. CISA names the product as N-able N-central.
Most families won’t have N-able N-central; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 3 Aug 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 6 Aug 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 15%. That’s in the top 4% 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
N-able has published a fix or advice.[3] CISA’s required action: “Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes).”[1]
- Check whether you use it.N-able N-central 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 6 Aug 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 8.1.[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 15%.[4] |
See also
Other N-able N-central flaws
- CVE-2026-86218: static code injection ·
- CVE-2026-18556: authentication bypass using an alternate path or channel ·
Other N-able flaws
- CVE-2025-8876, N-able N-Central: command injection ·
- CVE-2025-8875, N-able N-Central: insecure deserialization ·
Other authentication bypass flaws
- CVE-2026-20079, Cisco Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management: firewall management center authentication bypass using an alternate path or channel ·
- CVE-2026-19490, Citrix NetScaler: authentication bypass using an alternate path or channel ·
- CVE-2026-1603, Ivanti Endpoint Manager (EPM): authentication bypass ·
- CVE-2026-24858, Fortinet products: authentication bypass using an alternate path or channel ·
- CVE-2026-23760, SmarterTools SmarterMail: authentication bypass using an alternate path or channel ·
Every N-able flaw on CISA’s list · Everything added in August 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “N-able N-central Authentication Bypass Using an Alternate Path or Channel Vulnerability”. Known Exploited Vulnerabilities Catalog, added 3 Aug 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-18577 Detail”. National Vulnerability Database, published 2 Aug 2026.
- ^ N-able. Advisories and fixes: documentation.n-able.com, status.n-able.com, n-able.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.146, percentile 96.7, 31 Oct 2026.
- CVE Program. “CVE-2026-18577”. 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.