CVE-2026-81578: PaperCut NG/MF Missing Authentication for Critical Function Vulnerability
What it is
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.
What to do
Treat this as urgent. Identify every affected system, starting with anything internet-facing, and apply the vendor fix or mitigation within days. If you cannot patch quickly, isolate or disable the affected service and watch for signs of compromise.
- Priority
- Act now: Patch or mitigate internet-facing systems within days.
- Severity (CVSS)
- 8.8 high
- CISA assessment (SSVC)
- actively exploited; attackers can automate it at scale; partial control or data exposure
- Exploit probability (EPSS, 30 days)
- 86%, in the top 1% of all CVEs
- Added to CISA KEV
- 31 August 2026
- CISA fix-by date
- 14 September 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
- Weakness
- CWE-305
References
- NIST NVD entry
- CISA KEV entry
- www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81578
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.