{"id":"CVE-2026-81578","kind":"vulnerability","aliases":["CVE-2026-81578"],"related":[],"title":"An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG","description":"PaperCut NG/MF contains a missing authentication for critical function vulnerability which allows an unauthenticated remote attacker to modify certain system configurations. This vulnerability can be chained with CVE-2026-82078.\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":"Unauthenticated requests to PaperCut NG/MF web management admin functions run backend actions before access checks finish. An attacker can change system configuration. Chained with CVE-2026-82078 (unsafe class loading in the external card/ID DB lookup) this gives unauthenticated RCE as the PaperCut server process (SYSTEM on Windows). Exploited as a zero-day since about 26 Aug 2026. Attackers install SimpleHelp and AnyDesk. A public Metasploit module exists.","severity":"critical","cvss":9.8,"epss":null,"exploited":true,"exploited_at":"2026-08-31T00:00:00+00:00","products":[{"name":"PaperCut NG/MF","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"PaperCut NG/MF","fixed":["26.0.5","25.0.13","24.1.10"],"affected":"all versions before 26.0.5, 25.0.13, 24.1.10 (per NCSC IE; vendor says all versions until patched)","ecosystem":"vendor"},{"name":"papercut mf","fixed":["24.1.9"],"affected":"< 24.1.9","ecosystem":"vendor"},{"name":"papercut mf","fixed":["25.0.12"],"affected":">= 25.0.2, < 25.0.12","ecosystem":"vendor"},{"name":"papercut mf","fixed":["26.0.4"],"affected":">= 26.0.2, < 26.0.4","ecosystem":"vendor"},{"name":"papercut ng","fixed":["24.1.9"],"affected":"< 24.1.9","ecosystem":"vendor"},{"name":"papercut ng","fixed":["25.0.12"],"affected":">= 25.0.2, < 25.0.12","ecosystem":"vendor"},{"name":"papercut ng","fixed":["26.0.4"],"affected":">= 26.0.2, < 26.0.4","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","papercut-mf","papercut-ng","poc-public","print-server","rce-chain","self-hosted","vendor"],"not_affected_if":["managed-hosting"],"how_to_check":"Run version.txt or the admin UI to see your version; anything below 26.0.5, 25.0.13 or 24.1.10 is affected, and older than v24 is unsupported and affected. Search server.log for 'No suitable driver found for jdbc:no:x', 'DB URL: jdbc:derby:memory:pwn', 'Database error looking up cardID: VALUES CAST', 'DB URL: jdbc:no:x DB Driver:'. Look for server\\lib\\<5char>.class and server\\data\\content\\<5char>.cmd/.out, missing or truncated server.log, a Windows service 'Remote Access Service' (SimpleService.exe from C:\\ProgramData\\JWrapper-Remote Access), unexpected AnyDesk, and pc-app.exe spawning cmd.exe. Absence of these does not prove you are clean.","fix":"Upgrade the Application Server, Site Servers and secondary servers to PaperCut NG/MF 26.0.5, 25.0.13 or 24.1.10 (or later; the Sep bulletin mentions 24.1.11). Emergency Patch Release 3 also protects, but Releases 1 and 2 do not (the Metasploit PR bypasses patch 1). Until patched, restrict web access to the server to trusted internal IPs only. Anyone with an unexpected indicator should back up, wipe and rebuild the server, restore a clean backup and rotate credentials. If you use an external DB for card/ID lookups, reconfigure it after upgrade (it moves to security.properties).","status":"open","published_at":"2026-08-28T16:18:29+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:31:44+00:00","updated_at":"2026-10-23T23:44:52+00:00","category":"vendor","confidence":0.85,"triage":{"at":"2026-10-23T20:31:44Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor mitigation or patch per PaperCut's instructions; the affected and fixed versions are not stated in the sources.\nFollow CISA BOD 26-04 guidance for internet-facing assets.","summary":"PaperCut NG and MF print management servers have a missing authentication flaw on a critical function that lets an unauthenticated remote attacker change certain system configurations. CISA lists it as actively exploited and says it can be chained with CVE-2026-82078.","category":"vendor","who_cares":["papercut-ng","papercut-mf","self-hosted","print-server"],"confidence":0.8,"analyst_note":"Find affected and fixed PaperCut NG/MF versions and the vendor mitigation from PaperCut's security advisory; confirm whether CVE-2026-82078 is also exploited.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["managed-hosting"],"severity_if_unknown":"critical"},"cost_usd":0.00039,"input_tokens":2223,"output_tokens":336,"severity_before":"unknown"},"analyst_status":"done","analyst_note":"Find affected and fixed PaperCut NG/MF versions and the vendor mitigation from PaperCut's security advisory; confirm whether CVE-2026-82078 is also exploited.","search":"'-04':176C,202C,233C '-2026':19A,22A,85B,157C '-81578':20A,23A '-82078':86B,158C '2026':118B '26':116B,175C,201C,232C 'access':3A,73B 'accord':165C 'action':71B,161C 'adher':229C 'admin':67B 'allow':140C 'anydesk':123B 'appli':162C 'applic':199C 'asset':223C 'attack':77B,119B,144C 'aug':117B 'authent':134C 'backend':70B 'base':180C 'bod':174C,200C,231C 'card/id':93B 'certain':147C 'chain':55B,82B,154C 'chang':79B 'check':74B 'cisa':159C,172C,189C 'class':88B 'cloud':205C 'complianc':170C 'configur':81B,149C 'contain':131C 'control':4A 'critic':136C 'cve':18A,21A,84B,156C 'day':113B 'db':94B 'discontinu':208C 'ensur':169C,228C 'evalu':221C 'exist':6A,128B 'exploit':40B,108B 'exposur':226C 'extern':92B 'finish':75B 'follow':198C 'forens':191C 'function':68B,137C 'give':97B 'guidanc':187C,203C 'guidelin':235C 'host':58B 'improp':2A 'instal':120B 'instruct':168C 'interfac':11A 'internet':225C 'load':89B 'lookup':95B 'manag':10A,66B 'metasploit':126B 'mf':14A,29A,31A,33A,43B 'miss':133C 'mitig':163C,214C 'modifi':146C 'modul':127B 'ng':17A,35A,37A,39A,46B 'ng/mf':25A,27A,64B,130C 'note':186C,197C 'papercut':13A,16A,24A,26A,28A,30A,32A,34A,36A,38A,42B,45B,63B,102B,129C 'papercut-mf':41B 'papercut-ng':44B 'patch':234C 'poc':48B 'poc-publ':47B 'print':51B 'print-serv':50B 'priorit':177C 'process':104B 'product':212C 'public':49B,125B 'rce':54B,99B 'rce-chain':53B 'remot':143C 'request':61B 'requir':160C,193C 'respons':219C 'risk':182C 'run':69B 'secur':178C 'see':183C,194C 'self':57B 'self-host':56B 'server':52B,103B 'servic':206C 'simplehelp':121B 'sinc':114B 'stakehold':217C 'system':80B,105B,148C 'triag':192C 'unauthent':60B,98B,142C 'unavail':216C 'unsaf':87B 'updat':179C 'url':184C,195C 'use':209C 'vendor':59B,167C 'vulner':5A,138C,151C 'web':9A,65B 'window':107B 'zero':112B 'zero-day':111B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-08-28T16:18:29+00:00","kev":{"dateAdded":"2026-08-31","dueDate":"2026-09-14","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:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/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":"eb41dac7-0af8-4f84-9f6d-0272772514f4","poc_count":1,"sources":[{"source":"kev","external_id":"CVE-2026-81578","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-81578","severity":null,"published_at":"2026-08-31T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T14:39:37+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-81578:93","url":null,"severity":null,"published_at":"2026-10-23T21:31:58+00:00","modified_at":"2026-10-23T21:31:58+00:00","first_seen_at":"2026-10-23T21:31:58+00:00","fetched_at":"2026-10-23T21:31:58+00:00","note":"Read PaperCut's bulletin (27 Aug, updated 10 Sep), NCSC IE, Metasploit PR #21842, 25.0.13 release notes. Both CVEs are KEV-listed and exploited; the vendor says all versions are affected until patched. A public Metasploit module is merged. I did not search social posts. CVSS: vendor v4 gives 8.8 for this CVE and 9.4 for 82078. Sibling signal CVE-2026-82078 is the same chain."},{"source":"nvd","external_id":"CVE-2026-81578","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81578","severity":null,"published_at":"2026-08-28T16:18:29+00:00","modified_at":"2026-09-14T00:16:56+00:00","first_seen_at":"2026-10-23T23:44:52+00:00","fetched_at":"2026-10-23T23:44:52+00:00","note":null}],"documents":[{"id":1061,"url":"https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/","title":"PaperCut NG/MF Security Bulletin (27 Aug 2026), updated 10 Sep","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":1061,"url":"https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/","title":"PaperCut NG/MF Security Bulletin (27 Aug 2026), updated 10 Sep","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"fix","confidence":null,"note":null},{"id":1071,"url":"https://github.com/rapid7/metasploit-framework/pull/21842","title":"Metasploit module for CVE-2026-81578 + CVE-2026-82078 (merged 2026-09-03)","kind":"poc","source":"analyst","text":null,"published_at":null,"relation":"poc","confidence":null,"note":null},{"id":1073,"url":"https://www.ncsc.gov.ie/pdfs/2609020277_CVE-2026-81578_CVE-2026-82078.pdf","title":"NCSC Ireland advisory on PaperCut MF/NG zero-days","kind":"other","source":"analyst","text":null,"published_at":null,"relation":"describes","confidence":null,"note":null},{"id":1074,"url":"https://www.papercut.com/products/mf/release-history/25-0/","title":"PaperCut MF 25.0 release history (25.0.13 security fixes)","kind":"release","source":"analyst","text":null,"published_at":null,"relation":"fix","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"}