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Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2026-82078

PaperCut MF/NG

PaperCut / PaperCut MF/NG · affected before 24.1.10, 25.0.13, 26.0.5

View live feed Monitor via API Watch CVE-2026-82078
Severity
CVSS 9.4 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
0.9%
First observed
29 Aug 2026
Last observed
01 Sep 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-82078 is a vulnerability affecting PaperCut PaperCut MF/NG. An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG. The application...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

PaperCut / PaperCut MF/NG affected before 24.1.10, 25.0.13, 26.0.5.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG

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.

Vendor Product Affected Status
PaperCut PaperCut MF/NG Before 24.1.10, 25.0.13, 26.0.5 Affected
Published
28 Aug 2026
Exploitation Reported
27 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
High
User interaction
None

Tags

cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 27 Aug 2026

Independent exploitation attestation added to the Previdian record.

Active exploitation observed

Previdian sensor

First observed 20 Aug 2026

First-party sensor telemetry confirms matching exploitation attempts.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
PaperCut First 2026-08-27 20:32 UTC
Rapid7 2026-08-28 10:09 UTC
Previdian 2026-08-30 20:11 UTC
CISA 2026-08-31 14:20 UTC
CVE 2026-08-31 15:42 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Aggregate observations show the scale, recency, and distribution of activity without overstating sparse data.

13

Attempts observed

6

Unique attacker IPs

5

Attacker countries

BG · HK · NL · RU · US

1

Sensors observed

Exploitation attempts over the last 7 days

Daily events observed by Previdian sensors

Updated 02 Sep 2026

0
0
7
0
0
6
0
27 Aug 28 Aug 29 Aug 30 Aug 31 Aug 1 Sep 2 Sep

First observed 29 Aug 2026 · Last observed 01 Sep 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
5
User-Agents
7

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.4 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

EPSS

0.9%

Weaknesses

Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') CWE-470

Recent mention · Rapid7

PaperCut NG/MF Critical Zero-Day Exploited in the Wild

Overview On August 27, 2026, PaperCut Software published an urgent security advisory stating that it is investigating active exploitation of a vulnerability affecting PaperCut NG and PaperCut MF. PaperCut has confirmed customer incidents and is treating the issue as a security...

Read full advisory

Timeline

From disclosure to observed exploitation

  1. KEV confirmed by CVE

    Exploitation attested by an external source

  2. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  3. CVE published

    Vulnerability disclosed publicly

  4. KEV confirmed by Rapid7

    Exploitation attested by an external source

  5. CVE ID reserved

    Identifier reserved by the CNA

  6. Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  7. Observed by Previdian sensors

    Evidence-backed exploitation signal

  8. Indicators of compromise added (9)

    Indicators of compromise recorded

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-82078

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-82078",
  "confidence": "Confirmed",
  "cvss_score": 9.4,
  "cvss_estimated": false,
  "epss_score": 0.00926,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 13, "sensors": 1 }
}