CVE-2023-27350
CVE-2023-27350 is a security flaw in PaperCut MF/NG, printing software offices and schools use. Attackers can run their own code on PaperCut MF/NG. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 21 Apr 2023, and says ransomware gangs have used it.[1]
PaperCut MF/NG is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. PaperCut has published a fix or advice.
Description
CISA calls it an improper access control in PaperCut MF/NG. In its words: “PaperCut MF/NG contains an improper access control vulnerability within the SetupCompleted class that allows authentication bypass and code execution in the context of system.”[1]
The CVE record adds: “This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914). Authentication is not required to exploit this vulnerability. The specific flaw exists within the SetupCompleted class. The issue results from improper access control. An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-18987.”[2]
The underlying weakness is improper access control (CWE-284), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; PaperCut’s advisory has them[3]. CISA names the product as PaperCut MF/NG.
Most families won’t have PaperCut MF/NG; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 21 Apr 2023, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 12 May 2023 to fix it.[1] CISA says ransomware gangs have used it.
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
PaperCut has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.PaperCut MF/NG is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 12 May 2023 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4] |
See also
Other PaperCut flaws
- CVE-2026-82078, PaperCut NG/MF: unsafe reflection ·
- CVE-2026-81578, PaperCut NG/MF: missing authentication for critical function ·
- CVE-2023-27351, PaperCut NG/MF: improper authentication ·
- CVE-2023-2533, PaperCut NG/MF: cross-site request forgery (CSRF) ·
Other improper access control flaws
- CVE-2015-3306, ProFTPD: improper access control ·
- CVE-2026-21962, Oracle HTTP Server and Oracle Weblogic Server Proxy Plug-in: improper access control ·
- CVE-2026-56290, Joomlack Page Builder: improper access control ·
- CVE-2026-34908, Ubiquiti UniFi OS: improper access control ·
- CVE-2026-48907, Widget Factory Joomla Content Editor: improper access control ·
Added the same day
- CVE-2023-28432, MinIO: information disclosure ·
- CVE-2023-2136, Chrome and other Chromium browsers: chrome skia integer overflow ·
Every PaperCut flaw on CISA’s list · Everything added in April 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “PaperCut MF/NG Improper Access Control Vulnerability”. Known Exploited Vulnerabilities Catalog, added 21 Apr 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-27350 Detail”. National Vulnerability Database, published 20 Apr 2023.
- ^ PaperCut. Advisories and fixes: papercut.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2023-27350”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.