CVE-2026-81578 is a critical-severity (CVSS 9.8) CWE-305 vulnerability in papercut papercut mf. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-08-31) — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.
An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under specific conditions, unauthenticated remote requests targeting…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-08-31. Federal agencies were required to remediate by 2026-09-14.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2026-81578.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-81578 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under specific conditions, unauthenticated remote requests targeting administrative functions can trigger backend actions prior to the completion of access validation checks. This allows an unauthenticated remote attacker to modify certain system configurations.
Affected Products
papercut mfpapercutpapercut ngpapercutResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every papercut papercut mf deployment and check each version against the affected-products list above.
Fix
Apply the papercut papercut mf security patch or hotfix for CVE-2026-81578 on the affected version, following the vendor advisory for your exact build.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
How to detect CVE-2026-81578
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2026-81578 -u https://target- Template
- PaperCut NG/MF <=26.0.4 - Unauthenticated ConfigEditor Access via Tapestry Complex-Direct
- Severity
- critical
- Impact
- An unauthenticated remote attacker can bypass authentication to access the ConfigEditor administrative interface and modify arbitrary system configurations including database driver settings. When chained with CVE-2026-82078, full remote code execution is achievable with SYSTEM privileges on Windows or papercut user privileges on Linux.
- Remediation
- Update to PaperCut NG/MF version 26.0.5, 25.0.13, or 24.1.10 or later. As an immediate mitigation, restrict network access to the PaperCut web management interface (default ports 9191 and 9192) to trusted administrative IPs only.
Template by ProjectDiscovery nuclei-templates (darses, DhiyaneshDk), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2026-81578 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.