Patchfirst
CVE-2026-82078 KEVPublic exploit Critical · 9.1 EPSS 63.0%

PaperCut NG/MF Unsafe Reflection Vulnerability

PaperCut · NG/MF

Summary

PaperCut NG and PaperCut MF contain an unsafe dynamic class loading flaw in their database connection utilities, where driver class names taken from configurable settings are instantiated without checking against an allowlist. An attacker who can manipulate system configuration parameters, which requires high privileges, can cause arbitrary Java bytecode already on the application classpath to execute under the PaperCut server process's security context, with no user interaction needed and network access sufficient to reach the configuration.

Official description · NVD

An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG. The application instantiates database driver classes based on configurable driver names without validating against an allowlist of approved drivers. If an attacker can manipulate system configuration parameters, this enables the execution of arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process.

Breakdown
83.1 / 100
Exploited
Yes, in CISA KEV
Reports
1
Tactics
2/15

How an attack unfolds

Based on mappings. Select a step to see the evidence.
  1. How attackers get in

  2. What they do

Confirmed exploited 1 day before it was disclosed. Public exploit code (Metasploit) was available 1 day before disclosure.

  1. EU database marks exploitedPublic exploit codeMetasploit1 day before
  2. DisclosedFirst seen exploitedVulnCheck KEV evidenceday 0
  3. Added to CISA KEV+3 days

CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.

techniques

2 , grouped by in kill-chain order, 2 cited passages 2

Initial AccessTA0001

Exploit Public-Facing Application T1190 Medium
AI mapping from the description · how it is exploited

Exploit via externally reachable application config manipulation

If an attacker can manipulate system configuration parameters
From the official description (NVD) Original (opens in a new tab) ↗

ExecutionTA0002

Command and Scripting Interpreter T1059 Medium
AI mapping from the description · primary impact

Arbitrary bytecode execution in server process

enables the execution of arbitrary Java bytecode residing on the application classpath
From the official description (NVD) Original (opens in a new tab) ↗

Detection

0 rules for this CVE · 244 general rules for its techniques

Rules for this CVE

0 that reference CVE-2026-82078 directly.

CVE-specific rules are not available in this build. Search SigmaHQ ↗

Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.

What security researchers reported

Named in 1 threat report
1 reportesentire.com

Reports are matched by finding the exact id CVE-2026-82078 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.

Also mentioned in 50 community threat pulses (AlienVault OTX)

Weaker evidence

Pulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.

References

3 links, grouped by NVD tag
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