PaperCut MF/NG Improper Access Control
CVE-2023-27350 is a critical-severity improper access control vulnerability in NG from PaperCut, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected NG versions: 22.0.5 (Build 63914). The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on April 21, 2023, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Papercut Mf to 20.1.7 or 21.2.11 or 22.0.9, whichever matches your release line, or a later version.
- Update Papercut Ng to 20.1.7 or 21.2.11 or 22.0.9, whichever matches your release line, or a later version.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on papercut.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| PaperCut | NG | 22.0.5 (Build 63914) | Not stated |
| Papercut | Papercut Mf | 8.0 up to, but not including, 20.1.7; 21.0.0 up to, but not including, 21.2.11; 22.0.0 up to, but not including, 22.0.9 | 20.1.7, 21.2.11, 22.0.9 |
| Papercut | Papercut Ng | 8.0 up to, but not including, 20.1.7; 21.0.0 up to, but not including, 21.2.11; 22.0.0 up to, but not including, 22.0.9 | 20.1.7, 21.2.11, 22.0.9 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 3.0 | 9.8 | Critical | CNA (trendmicro.com) |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- packetstormsecurity.com/files/171982/PaperCut-MF-NG-Authentication-Bypass-Remote-Code-Execution.htmlThird Party Advisory, VDB Entry
- news.sophos.com/en-us/2023/04/27/increased-exploitation-of-papercut-drawing-blood-around-the-internet/Third Party Advisory
- zerodayinitiative.com/advisories/ZDI-23-233/Third Party Advisory, VDB Entry
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-27350US Government Resource
Technical write-ups (may include proof of concept)
- packetstormsecurity.com/files/172022/PaperCut-NG-MG-22.0.4-Authentication-Bypass.htmlExploit, Third Party Advisory, VDB Entry
- packetstormsecurity.com/files/172512/PaperCut-NG-MG-22.0.4-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- packetstormsecurity.com/files/172780/PaperCut-PaperCutNG-Authentication-Bypass.htmlExploit, Third Party Advisory, VDB Entry
Other vulnerabilities in NG
- 7.2 High severity
- 7.2 High severity
- 7.5 High severity
PaperCut NG/MF Improper Authentication Exploited
Recent Improper Access Control vulnerabilities
- 7.7 High severity
- 7.1 High severity
- 8.3 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.