Patchfirst
CVE-2026-81578 KEVPublic exploit Critical · 9.8 EPSS 84.7%

PaperCut NG/MF Missing Authentication for Critical Function Vulnerability

PaperCut · NG/MF

Summary

A flaw in the web management interface of PaperCut MF and PaperCut NG lets backend actions on administrative functions run before access validation completes. An unauthenticated attacker with network access to that interface can, under specific conditions, send remote requests to modify certain system configurations, with no user interaction required.

Official description · NVD

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.

Breakdown
83.7 / 100
Exploited
Yes, in CISA KEV
Reports
1
Tactics
3/15

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

unauthenticated remote request to public web interface

unauthenticated remote requests targeting administrative functions
From the official description (NVD) Original (opens in a new tab) ↗

PersistenceTA0003

Account Manipulation T1098 Medium also Privilege Escalation
AI mapping from the description · primary impact

attacker modifies system configuration settings

allows an unauthenticated remote attacker to modify certain system configurations
From the official description (NVD) Original (opens in a new tab) ↗

Detection

0 rules for this CVE · 184 general rules for its techniques

Rules for this CVE

0 that reference CVE-2026-81578 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-2026-81578 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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