CyberSecBulletin
CVE-2026-18556Exploited in the wildNVD status: Analyzed

N-able N-central Authentication Bypass Using an Alternate Path or Channel

Published Updated By the CyberSecBulletin desk

CVE-2026-18556 is a high-severity authentication bypass using an alternate path or channel vulnerability in N-central from N-able, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected N-central versions: 2026.1 and earlier. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on August 4, 2026, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Check which version of N-central you run against the affected versions below, and install the vendor's latest release.
  2. 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). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
  3. Read the advisory on uptime.n-able.com for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
N-ableN-central2026.1 and earlierNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.08.2HighCNA
CVSS 3.17.4HighNVD

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Authentication Bypass Using an Alternate Path or Channel

The product requires authentication, but the product has an alternate path or channel that does not require authentication.

How developers prevent this class of flaw

  • Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.

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

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  3. Added to CISA's Known Exploited Vulnerabilities catalogue.
  4. Deadline for US federal agencies to remediate, set by CISA.
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in N-central

All N-central vulnerabilities

Recent Authentication Bypass Using an Alternate Path or Channel vulnerabilities

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