CVE-2026-82078: PaperCut NG/MF Unsafe Reflection Vulnerability
What it is
PaperCut NG/MF contains an unsafe reflection vulnerability that allows an attacker to manipulate system configuration parameters and execute arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process. This vulnerability can be chained with CVE-2026-81578.
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)
- 9.4 critical
- CISA assessment (SSVC)
- actively exploited; needs manual effort per target; total control of the affected system
- Exploit probability (EPSS, 30 days)
- 64%, 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-470
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-2026-82078
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.