How severe is CVE-2026-81578?

No CVSS score has been assigned to CVE-2026-81578 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-81578?

Affected package information for CVE-2026-81578 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-81578?

No fixed release is recorded for CVE-2026-81578 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2026-81578 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2026-81578 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-81578 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2026-81578, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2026-81578?

CVE-2026-81578 has an EPSS (Exploit Prediction Scoring System) score of 84.6%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2026-81578 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-81578 (PaperCut NG/MF Missing Authentication for Critical Function Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-08-31. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-09-14. The required action was: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-81578?

CVE-2026-81578 is classified as CWE-305 (CWE-305). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2026-81578?

A Nuclei detection template exists for CVE-2026-81578, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2026-81578 published, and has it been updated?

CVE-2026-81578 was published on August 28, 2026 and was last updated on September 13, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV · ACTIVELY EXPLOITED

CVE-2026-81578 — Rapid7

Fix: rapid7/metasploit-framework#21842

CVE-2026-81578 is a CWE-305 vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-08-31) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under specific conditions, unauthenticated remote requests targeting…

Published

Aug 28, 2026

Updated

Sep 13, 2026

Affected

2 products

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 6, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-08-31. Federal agencies were required to remediate by 2026-09-14.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2026-81578.

EPSS Exploitation Probability

via FIRST.org ↗

84.6%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Description

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.

Affected Products

2 products · 6 configurations

Application

papercut mfpapercut

≥ 26.0.2 && < 26.0.4

range

Application

papercut ngpapercut

≥ 26.0.2 && < 26.0.4

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

yora1928/PaperCut-CVE-2026-81578-82078

Security research tool for PaperCut CVE-2026-81578 & CVE-2026-82078

⭐ 4🍴 0Sep 2026

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2026-81578 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

How to detect CVE-2026-81578

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2026-81578 -u https://target

Template: PaperCut NG/MF <=26.0.4 - Unauthenticated ConfigEditor Access via Tapestry Complex-Direct
Severity: critical
Impact: An unauthenticated remote attacker can bypass authentication to access the ConfigEditor administrative interface and modify arbitrary system configurations including database driver settings. When chained with CVE-2026-82078, full remote code execution is achievable with SYSTEM privileges on Windows or papercut user privileges on Linux.
Remediation: Update to PaperCut NG/MF version 26.0.5, 25.0.13, or 24.1.10 or later. As an immediate mitigation, restrict network access to the PaperCut web management interface (default ports 9191 and 9192) to trusted administrative IPs only.

Template by ProjectDiscovery nuclei-templates (darses, DhiyaneshDk), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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