# CVE-2026-81578: PaperCut NG/MF Missing Authentication for Critical Function

> Unauthenticated attackers can bypass access controls to modify system configurations in PaperCut MF/NG web interfaces.

- **Severity:** High 8.8 (`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`)
- **Exploited in the wild:** Yes, since 31 Aug 2026 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Aug 2026
- **Updated:** 13 Sep 2026
- **Also known as:** GHSA-44wc-j6f2-7fjr

## What is CVE-2026-81578?

CVE-2026-81578 is a high-severity authentication bypass vulnerability in PaperCut MF/NG, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-305 (Authentication Bypass by Primary Weakness)

## Which versions are affected by CVE-2026-81578?

It affects 2 products.


Products: Papercut Papercut Mf, Papercut Papercut Ng.

## How do I fix CVE-2026-81578?

No fix has been published for CVE-2026-81578 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 14 Sep 2026.

## Is CVE-2026-81578 being exploited?

Yes. Attackers have exploited CVE-2026-81578 in the wild since at least 31 Aug 2026.

Public exploit code:

- Security research tool for PaperCut CVE-2026-81578 & CVE-2026-82078 (github_poc): https://github.com/yora1928/PaperCut-CVE-2026-81578-82078
- #PaperCut CVE-2026-81578 + CVE-2026-82078 Defense Toolkit 2 3 A **defensive** toolkit to check and understand exposure to the chained (github_poc): https://github.com/virologi-info/papercut-toolkit
- PaperCut NG/MF Unauthenticated RCE (CVE-2026-81578 + CVE-2026-82078) (metasploit)
- PaperCut NG/MF <=26.0.4 - Unauthenticated ConfigEditor Access via Tapestry Complex-Direct (nuclei): http/cves/2026/CVE-2026-81578.yaml

## Other vulnerabilities in PaperCut MF/NG

- [CVE-2023-27350](https://insights.sbomify.com/CVE-2023-27350/): PaperCut MF/NG Improper Access Control (critical 9.8, exploited in the wild)
- [CVE-2026-82078](https://insights.sbomify.com/CVE-2026-82078/): PaperCut NG/MF Unsafe Reflection (critical 9.4, exploited in the wild)
- [CVE-2023-2533](https://insights.sbomify.com/CVE-2023-2533/): PaperCut NG/MF Cross-Site Request Forgery (CSRF) (high 8.4, exploited in the wild)
- [CVE-2023-27351](https://insights.sbomify.com/CVE-2023-27351/): PaperCut NG/MF Improper Authentication (high 8.2, exploited in the wild)
- [CVE-2023-39143](https://insights.sbomify.com/CVE-2023-39143/): Path traversal in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81578 and fix it if it is affected.

What it is: CVE-2026-81578 is a high-severity authentication bypass vulnerability in PaperCut MF/NG, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2026-81578 in the wild since at least 31 Aug 2026.

Affected product: PaperCut MF/NG. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-81578/ (Markdown: https://insights.sbomify.com/CVE-2026-81578/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81578
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81578
- OSV: https://osv.dev/vulnerability/CVE-2026-81578

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81578/
Summaries are generated and may contain mistakes; the official description above is the record.