Which versions of N-able N-central are affected by CVE-2026-18556?

N-able N-central versions through 2026.1 contain an authentication bypass vulnerability allowing unauthenticated external attackers to access management infrastructure without credentials, posing…

Is there a public PoC exploit available for CVE-2026-18556?

Yes, a public proof-of-concept exploit is available for CVE-2026-18556. Prioritise patching immediately. EPSS: 0.3%.

How to fix or mitigate CVE-2026-18556?

Within 24 hours, identify all N-able N-central instances running version 2026.1 or earlier and segment them from untrusted networks using access control lists that restrict connectivity to authorized administrative sources only. Over the next 7 days, deploy Web Application Firewall or reverse proxy rules to block requests to alternate authentication endpoints, implement comprehensive logging for authentication and API access attempts, and establish real-time alerting for exploitation indicators. Within 30 days, contact N-able to obtain a patch release timeline for CVE-2026-18556, document your interim controls for compliance records, and prepare a staged deployment plan for patched versions upon availability.

N-able N-central CVE-2026-18556

Q: What is the CVSS score of CVE-2026-18556?

CVE-2026-18556 has a CVSS 4.0 base score of 8.2 (High). CVSS vector: 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. EPSS exploitation probability: 0.3%.

EUVD-2026-51918 HIGH

Authentication Bypass Using an Alternate Path or Channel (CWE-288)

2026-08-01 a5532a13-c4dd-4202-bef1-e0b8f2f8d12b

Authentication Bypass N Central N Able

8.2

CVSS 4.0 · Vendor: a5532a13-c4dd-4202-bef1-e0b8f2f8d12b

Severity by source

Vendor (a5532a13-c4dd-4202-bef1-e0b8f2f8d12b) PRIMARY

8.2 HIGH

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

ENISA EUVD

HIGH

qualitative

vuln.today AI

5.9 MEDIUM

Network vector and no-auth are confirmed; AC:H reflects the non-trivial alternate-path discovery requirement; no integrity or availability impact per the CVSS 4.0 VC:H/VI:N/VA:N mapping.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (a5532a13-c4dd-4202-bef1-e0b8f2f8d12b).

CVSS VectorVendor: a5532a13-c4dd-4202-bef1-e0b8f2f8d12b

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Threat Model Generated

Aug 31, 2026 - 11:58 vuln.today

Added to CISA KEV

Aug 04, 2026 - 17:16 CISA

Analysis Generated

Aug 01, 2026 - 20:30 vuln.today

CVE Published

Aug 01, 2026 - 20:16 cve.org

HIGH 8.2

DescriptionCVE.org

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.

Articles & Coverage 1

POC CVE-2026-18556 & CVE-2026-18577: Authentication Bypass in N-able N-central Under Active Exploitation Aug 06, 2026

AnalysisAI

Authentication bypass in N-able N-central through version 2026.1 allows unauthenticated remote attackers to circumvent authentication controls via an alternate path or channel (CWE-288), resulting in high confidentiality impact against the vulnerable system. The CVSS 4.0 vector (AV:N/AC:H/PR:N/UI:N/VC:H) indicates exploitation requires elevated attack complexity but no credentials, suggesting a non-trivial bypass technique such as direct access to an unauthenticated API endpoint or alternate URL path that bypasses the primary authentication gateway. No public exploit code has been identified at time of analysis, and the vulnerability is not listed in CISA KEV.

Technical ContextAI

N-able N-central is an enterprise Remote Monitoring and Management (RMM) platform widely deployed by Managed Service Providers (MSPs) to manage client endpoints. CWE-288 - Authentication Bypass Using an Alternate Path or Channel - describes a class of vulnerabilities where an application enforces authentication on its primary interface but exposes a secondary access path (such as a direct internal API endpoint, an unauthenticated management servlet, or a legacy protocol interface) that bypasses the authentication layer entirely. This is distinct from credential-based bypass and typically requires knowledge of the alternate route. The affected scope is N-central through version 2026.1; no CPE string was included in the provided data, and the sole reference points only to the N-able service status page (uptime.n-able.com), not a formal security advisory.

RemediationAI

No vendor-released patch has been independently confirmed at time of analysis - the only provided reference (https://uptime.n-able.com/) is a service status page, not a security advisory. Organizations should monitor the N-able security advisories page and N-central release notes for a patched version beyond 2026.1. As compensating controls pending a patch, restrict N-central management interface access to known MSP operator IP ranges via network ACLs or firewall rules to reduce the exposure surface for network-based bypass attempts; this directly addresses the AV:N vector. Additionally, review network segmentation to ensure N-central is not internet-facing without a VPN or jump-host boundary, given that AC:H exploitation still requires network reachability. Enabling enhanced authentication logging on the platform can help detect anomalous access patterns indicative of bypass attempts. These controls reduce but do not eliminate risk - a patch from N-able remains the authoritative remediation.