Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:H) | High complexity |
| Attack requirements (AT:N) | No attack requirements |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Confidentiality (VC:H) | High confidentiality impact |
| Integrity (VI:N) | No integrity impact |
| Availability (VA:N) | No availability impact |
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CISA required action
About N-able N-central
CVE-2026-18556 affects N-able N-central, a product from N-able. Before acting, confirm where N-able N-central runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: Authentication bypass using an alternate path or channel vulnerability in N-able N-central allows Authentication Bypass. This issue affects N-central: through 2026.1.
The weakness class is Authentication Bypass via Alternate Path. A second route into the app skips the login check.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | N-able N-central |
| Affected versions | N-Central up to and including 2026.1 |
| Published | Aug 1, 2026 |
| Last modified | Aug 5, 2026 |
| Added to CISA KEV | Aug 4, 2026 |
| Assigning CNA | a5532a13-c4dd-4202-bef1-e0b8f2f8d12b |
How to detect it
- Inventory every instance of N-able N-central and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of N-able N-central named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on N-able N-central to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Known exploited, so top priority. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-288: Authentication Bypass via Alternate Path More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
N-central is vulnerable to a pre-auth remote code execution This issue affects N-central: before 2026.3.1.14.
An incomplete patch for CVE-2026-18556 allows for authentication bypass and account takeover in N-central Versions through 2026.3.1
Authentication Bypass Using an Alternate Path or Channel vulnerability in Nuvation Energy Multi-Stack Controller (MSC) allows Authentication Bypass.This issue affects Multi-Stack Controller (MSC): from 2.3.8 before 2.5.1.
An Authentication Bypass vulnerability (CWE-288) in Ivanti Sentry before the R10.5.2, R10.6.2 and R10.7.1 versions allows a remote unauthenticated attacker to create arbitrary administrative accounts and obtain full administrative access
Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Mitigation bypass in the Networking: Cache component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-18556 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications