{"id":"CVE-2026-18556","kind":"vulnerability","aliases":["CVE-2026-18556"],"related":[],"title":"Authentication bypass using an alternate path or channel vulnerability in N-able N-central allows Authentication Bypass","description":"N-able N-central contains an authentication bypass using an alternate path or channel that allows for authentication bypass.\n\nCISA 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.","summary":"Authentication bypass (CWE-288) in N-able N-central through 2026.1, exploited in the wild since Jul 31 and on CISA KEV since Aug 4. It gives remote admin access without login. Attackers used Take Control to reach managed devices and installed Cloudflared tunnels for persistence. Hotfix 1 (2026.3.1.7) came out Aug 2 and was followed by Hotfix 2 (2026.3.1.10) on Aug 6, which supersedes it. Companion CVE-2026-18577 is a related bypass in the same incident. N-able's hosted environments were mitigated by N-able; on-prem is the exposure.","severity":"high","cvss":8.2,"epss":null,"exploited":true,"exploited_at":"2026-08-04T00:00:00+00:00","products":[{"name":"N-able N-central","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"N-able N-central","fixed":["2026.3.1.10"],"affected":"<= 2026.1 (vendor says Hotfix 2 needed: < 2026.3.1.10)","ecosystem":"vendor"},{"name":"n-able n-central","fixed":[],"affected":"<= 2026.1","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","msp","n-able","n-central","on-prem","rmm","self-hosted","vendor"],"not_affected_if":["managed-hosting","not-n-central"],"how_to_check":"Check the N-central server version in the admin UI. Anything below 2026.3.1.10 is exposed. Look for IOCs: svchost.exe in a user's Documents folder, a Cloudflared service on endpoints, unexpected new users or password resets, unusual Take Control sessions, and traffic from 173.249.252.200, 185.156.46.150, 23.234.94.43, 37.153.90.88, 37.19.210.32, 68.235.46.214, 68.235.46.235, 87.249.138.34, 92.118.112.181. N-able offers a detection template at developer.n-able.com/n-central/recipes/cve-2026-18577-detection.","fix":"Upgrade to N-central 2026.3.1 Hotfix 2 (2026.3.1.10). It supersedes Hotfix 1 (2026.3.1.7). If you patched late, assume compromise: audit accounts, reset credentials, enforce MFA, and disable the in-product support account unless a support case needs it.","status":"open","published_at":"2026-08-01T20:16:37+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:32:02+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"vendor","confidence":0.8,"triage":{"at":"2026-10-23T20:32:02Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor mitigation or patch from N-able as CISA directs under BOD 26-04; if no mitigation is available, discontinue use of the product per CISA guidance.","summary":"N-able N-central, a remote monitoring and management platform for managed service providers, has an authentication bypass through an alternate path or channel. An attacker can get past login and act as an authenticated user, and CISA lists it as actively exploited.","category":"vendor","who_cares":["n-able","n-central","msp","rmm"],"confidence":0.6,"analyst_note":"Find N-able's advisory and the affected/fixed N-central versions and check whether the exposed interface is internet-facing; the CISA KEV entry at cisa.gov/known-exploited-vulnerabilities-catalog gives no version data.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["not-n-central"],"severity_if_unknown":"high"},"cost_usd":0.000379,"input_tokens":2181,"output_tokens":322,"severity_before":"unknown"},"analyst_status":"done","analyst_note":"Find N-able's advisory and the affected/fixed N-central versions and check whether the exposed interface is internet-facing; the CISA KEV entry at cisa.gov/known-exploited-vulnerabilities-catalog gives no version data.","search":"'-04':196C,222C,253C '-18556':22A,25A '-18577':131B '-2026':21A,24A,130B '-288':63B '1':109B '2':114B,120B '2026.1':72B '2026.3.1.10':121B '2026.3.1.7':110B '26':195C,221C,252C '31':79B '4':86B '6':124B 'abl':13A,48B,67B,142B,151B,160C 'able':28A,34A,40A 'access':91B 'accord':185C 'action':181C 'adher':249C 'admin':90B 'allow':17A,175C 'altern':5A,170C 'appli':182C 'applic':219C 'asset':243C 'attack':94B 'aug':85B,113B,123B 'authent':1A,18A,60B,166C,177C 'base':200C 'bod':194C,220C,251C 'bypass':2A,19A,61B,135B,167C,178C 'came':111B 'central':16A,31A,37A,43A,51B,70B,163C 'channel':8A,173C 'cisa':82B,179C,192C,209C 'cloud':225C 'cloudflar':104B 'companion':128B 'complianc':190C 'contain':164C 'control':97B 'cve':20A,23A,129B 'cwe':62B 'devic':101B 'discontinu':228C 'ensur':189C,248C 'environ':145B 'evalu':241C 'exploit':44B,73B 'exposur':157B,246C 'follow':117B,218C 'forens':211C 'give':88B 'guidanc':207C,223C 'guidelin':255C 'host':58B,144B 'hotfix':108B,119B 'incid':139B 'instal':103B 'instruct':188C 'internet':245C 'jul':78B 'kev':83B 'login':93B 'manag':100B 'mitig':147B,183C,234C 'msp':45B 'n':12A,15A,27A,30A,33A,36A,39A,42A,47B,50B,66B,69B,141B,150B,159C,162C 'n-abl':11A,46B,65B,140B,149B,158C 'n-able':26A,32A,38A 'n-central':14A,29A,35A,41A,49B,68B,161C 'note':206C,217C 'on-prem':52B,152B 'patch':254C 'path':6A,171C 'persist':107B 'prem':54B,154B 'priorit':197C 'product':232C 'reach':99B 'relat':134B 'remot':89B 'requir':180C,213C 'respons':239C 'risk':202C 'rmm':55B 'secur':198C 'see':203C,214C 'self':57B 'self-host':56B 'servic':226C 'sinc':77B,84B 'stakehold':237C 'supersed':126B 'take':96B 'triag':212C 'tunnel':105B 'unavail':236C 'updat':199C 'url':204C,215C 'use':3A,95B,168C,229C 'vendor':59B,187C 'vulner':9A 'wild':76B 'without':92B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-08-01T20:16:37+00:00","kev":{"dateAdded":"2026-08-04","dueDate":"2026-08-07","requiredAction":"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.","knownRansomwareCampaignUse":"Unknown"},"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","cvss_by":"a5532a13-c4dd-4202-bef1-e0b8f2f8d12b","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2026-18556","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-18556","severity":null,"published_at":"2026-08-04T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T20:35:31+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-18556:133","url":null,"severity":null,"published_at":"2026-10-23T21:42:29+00:00","modified_at":"2026-10-23T21:42:29+00:00","first_seen_at":"2026-10-23T21:42:29+00:00","fetched_at":"2026-10-23T21:42:29+00:00","note":"Vendor blog (N-able, Aug 10), Cyber Centre AV26-769 and CVE record read. N-able's own CVE-2026-18556 advisory page was not found; the fix version comes from the vendor blog. No X chatter found."},{"source":"nvd","external_id":"CVE-2026-18556","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-18556","severity":null,"published_at":"2026-08-01T20:16:37+00:00","modified_at":"2026-10-23T22:10:00+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+00:00","note":null}],"documents":[{"id":1214,"url":"https://www.n-able.com/blog/n-central-security-update-august-10-2026","title":"N-central Security Update – August 10, 2026","kind":"vendor","source":"analyst","text":null,"published_at":null,"relation":"fix","confidence":null,"note":null},{"id":1215,"url":"https://www.cyber.gc.ca/en/alerts-advisories/n-able-security-advisory-av26-769","title":"Cyber Centre AV26-769 N-able advisory","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":1218,"url":"https://www.cve.org/CVERecord?id=CVE-2026-18556","title":"CVE Record CVE-2026-18556","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"describes","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}