CVE-2023-2533: PaperCut NG/MF Cross-Site Request Forgery (CSRF) Vulnerability

What it is

A Cross-Site Request Forgery (CSRF) vulnerability has been identified in PaperCut NG/MF, which, under specific conditions, could potentially enable an attacker to alter security settings or execute arbitrary code. This could be exploited if the target is an admin with a current login session. Exploiting this would typically involve the possibility of deceiving an admin into clicking a specially crafted malicious link, potentially leading to unauthorized changes.

Exploitation evidence

First exploit evidence seen: 2025-07-28 (earliest date across the sources below).

Exploited in the wild

• CISA KEV: listed since 2025-07-28. Source

Sources: CISA KEV.

How to fix it

CISA required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. (source: CISA KEV)

Fixed versions

• papercut papercut mf: upgrade to 20.1.8 or later
• papercut papercut mf: upgrade to 21.2.12 or later (affected from 21.0.0)
• papercut papercut mf: upgrade to 22.1.1 or later (affected from 22.0.0)
• papercut papercut ng: upgrade to 20.1.8 or later
• papercut papercut ng: upgrade to 21.2.12 or later (affected from 21.0.0)

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

• https://www.papercut.com/kb/Main/SecurityBulletinJune2023 (CISA KEV notes)

MITRE ATT&CK mitigations for this chain

• M1054 Software Configuration (for T1566.002) : Use anti-spoofing and email authentication mechanisms to filter messages based on validity checks of the sender domain (using SPF) and integrity of messages (using DKIM). Enabling these mechanisms within an organization (through policies such as DMARC) may enable recipients (intra-org and cross domain) to perform simil
• M1021 Restrict Web-Based Content (for T1566.002, T1059) : Determine if certain websites that can be used for spearphishing are necessary for business operations and consider blocking access if activity cannot be monitored well or if it poses a significant risk.
• M1047 Audit (for T1566.002, T1059) : Audit applications and their permissions to ensure access to data and resources are limited based upon necessity and principle of least privilege.
• M1018 User Account Management (for T1566.002) : Azure AD Administrators apply limitations upon the ability for users to grant consent to unfamiliar or unverified third-party applications.
• M1017 User Training (for T1566.002) : Users can be trained to identify social engineering techniques and spearphishing emails with malicious links which includes phishing for consent with OAuth 2.0. Additionally, users may perform visual checks of the domains they visit; however, homographs in ASCII and in IDN domains and URL schema obfuscation may render
• M1033 Limit Software Installation (for T1059) : Prevent user installation of unrequired command and scripting interpreters.
• M1045 Code Signing (for T1059) : Where possible, only permit execution of signed scripts.
• M1042 Disable or Remove Feature or Program (for T1059) : Disable or remove any unnecessary or unused shells or interpreters.
• M1038 Execution Prevention (for T1059) : Use application control where appropriate. For example, PowerShell Constrained Language mode can be used to restrict access to sensitive or otherwise dangerous language elements such as those used to execute arbitrary Windows APIs or files (e.g., `Add-Type`).
• M1049 Antivirus/Antimalware (for T1059) : Anti-virus can be used to automatically quarantine suspicious files.

Detection Generic guidance

• Initial Access: Alert on unusual requests to the affected service (odd paths, oversized payloads, exploit strings) in WAF, reverse-proxy and application logs.
• Execution: Watch for the service process spawning shells or script interpreters (cmd.exe, powershell, sh, bash, python) via EDR process-tree rules.
• Persistence: Look for new files in web roots, new scheduled tasks/services, and new accounts created after the exposure window.
• Privilege Escalation: Alert on processes gaining SYSTEM/root unexpectedly, and on exploitation crashes of privileged services.

Response checklist Generic guidance

1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.