# PaperCut MF/NG auth bypass to SYSTEM RCE, used by Cl0p and LockBit (CVE-2023-27350) · pwn.watch

> An improper access control bug in PaperCut NG/MF print management let unauthenticated attackers run code as SYSTEM. Fixes had shipped in March 2023, but unpatched servers were exploited from April. Microsoft linked it to Cl0p (Lace Tempest) and LockBit, and the Bl00dy gang hit schools with it.

Page: https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350 · generated 2026-10-22T23:52:53.443Z

## Status
- Severity: critical · status: closed · patch: patched
- Product: PaperCut MF and PaperCut NG
- Started: 2023-04-21 · closed: 2023-05-11
- CVEs: CVE-2023-27350
- Affected: See vendor advisory
- Fixed in: 20.1.7; 21.2.11; 22.0.9

## Follow this incident
- RSS (one item per update): https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350/feed.xml
- JSON Feed: https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350/feed.json
- Full data (timeline, sources, posts, agentBrief): https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350.json
- This file: https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350/llms.txt

## Updates (newest first)
- 2023-05-11: CISA and FBI advisory AA23-131A: Bl00dy Ransomware Gang targeting education via PaperCut (https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-131a)
- 2023-04-21: PaperCut warns that unpatched servers are being exploited in the wild; CISA adds CVE-2023-27350 to KEV (https://www.papercut.com/kb/Main/PO-1216-and-PO-1219)

## Fix brief
# Security brief: PaperCut MF/NG auth bypass to SYSTEM RCE, used by Cl0p and LockBit (CVE-2023-27350)

Source: https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350 · status: closed (closed May 11, 2023) · severity: critical · updated May 11, 2023

## Patch status
**PATCHED: fixed releases exist. Upgrade to a fixed version.**

## What it is
An improper access control bug in PaperCut NG/MF print management let unauthenticated attackers run code as SYSTEM. Fixes had shipped in March 2023, but unpatched servers were exploited from April. Microsoft linked it to Cl0p (Lace Tempest) and LockBit, and the Bl00dy gang hit schools with it.

Severity detail: CVSS 9.8 (NVD), actively exploited (CISA KEV), known ransomware use

- Product: PaperCut MF and PaperCut NG
- CVE / advisory ids: CVE-2023-27350

## Affected versions
- See vendor advisory

## Check whether you're affected
No generic command applies (the product is a hosted service, appliance or desktop app). Check the installed version in its admin UI / About screen and compare with the versions above.

## Fix
Upgrade to one of these fixed versions (or later on the same branch):
- 20.1.7
- 21.2.11
- 22.0.9

After upgrading, re-run the checks above and redeploy/restart the affected services.

## Latest updates
- May 11, 2023: CISA and FBI advisory AA23-131A: Bl00dy Ransomware Gang targeting education via PaperCut
- Apr 21, 2023: PaperCut warns that unpatched servers are being exploited in the wild; CISA adds CVE-2023-27350 to KEV

## Advisories
- [URGENT | PaperCut MF/NG vulnerability bulletin (PO-1216 and PO-1219)](https://www.papercut.com/kb/Main/PO-1216-and-PO-1219) (PaperCut)
- [Malicious Actors Exploit CVE-2023-27350 in PaperCut MF and NG (AA23-131A)](https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-131a) (CISA)
- [NVD: CVE-2023-27350](https://nvd.nist.gov/vuln/detail/CVE-2023-27350) (NVD)
- [CISA Known Exploited Vulnerabilities Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog) (CISA)

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Machine-readable: https://pwn.watch/i/papercut-mf-ng-auth-bypass-cve-2023-27350.json · all incidents: https://pwn.watch/incidents.json. Verify against the vendor advisory before changing production systems.