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CVE-2026-81578· NVD / CVE Program· CNA PaperCut

PaperCut MF/NG: Authentication Bypass

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.

HighCVSS 8.8 · v4.0KEVWeaponized Fix available
Published
Aug 28, 2026
Updated
Sep 13, 2026
EPSS
4.5% · 91th percentile
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Report tools

JSON

Action score

66

This week

Don’t wait for the next maintenance window.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
30 / 30 · Listed
EPSS
1 / 30 · 4.5%

CISA SSVC decision

Exploitation
active
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · PaperCut
8.8
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Aug 31, 2026. That signals real attacks, not theory.

Remediation deadline for government agencies: Sep 14, 2026.

Affected systems

VendorProduct
papercutpapercut mf
papercutpapercut ng

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • papercut papercut mfbefore 24.1.9
  • papercut papercut mf25.0.2 and later · before 25.0.12
  • papercut papercut mf26.0.2 and later · before 26.0.4
  • papercut papercut ngbefore 24.1.9
  • papercut papercut ng25.0.2 and later · before 25.0.12
  • papercut papercut ng26.0.2 and later · before 26.0.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (PaperCut). Independent of NVD's CPE analysis and usually ahead of it.

  • PaperCut PaperCut MF/NG

    • before 24.1.10affected · semver
    • 25.0.0 and later · before 25.0.13affected · semver
    • 26.0.0 and later · before 26.0.5affected · semver

Same product

papercut: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-27350This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914).KEV
    99Now
  • CVE-2023-27351This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914).KEV
    83Now
  • CVE-2023-2533PaperCut MF/NG 22.0.10 (Build 65996 2023-03-27) - Remote code execution via CSRFKEV
    74This week
  • CVE-2026-82078PaperCut MF/NG: Unsafe Dynamic Class Loading in Database ConnectorKEV
    68This week
  • CVE-2023-39143PaperCut NG and PaperCut MF before 22.1.3 on Windows allow path traversal, enabling attackers to upload, read, or delete arbitrary files.
    63This week
  • CVE-2024-1222Incorrect authorization controls in PaperCut NG/MF APIs
    58Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PaperCut PaperCut MF/NG24.1.10Vendor (CNA)
PaperCut PaperCut MF/NG25.0.13Vendor (CNA)
PaperCut PaperCut MF/NG26.0.5Vendor (CNA)

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

  • Metasploit module ×1
  • Nuclei detection template ×1
  • Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Metasploit moduleexploit/multi/http/papercut_ng_external_user_lookup_rcePaperCut NG/MF Unauthenticated RCE (CVE-2026-81578 + CVE-2026-82078)exploit2026-08-27
Nuclei detection templateNuclei template CVE-2026-81578 —
Proof-of-concept repository on GitHubstars:42026-08-29
Proof-of-concept repository on GitHubstars:22026-08-29

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Metasploit-2 d
  2. Published
  3. First PoCsame day
  4. CISA KEV+2 d
  5. TodaySep 29, 2026+32 d
EPSS, last 120 days+1% in 7 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

—

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-6418115 days apartPaperCut NG/MF: Path Traversal in Shared Account Synchronization
    18Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-305 · Authentication Bypass by Primary Weakness

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records