PatchTheCEVCVE-2026-81578: PaperCut NG/MF Missing Authentication for Critical Function Vulnerability
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CRITICAL 9.8EXPLOITEDREMOTEUPGRADEUPGRADE
CVE-2026-81578 is a critical-severity flaw (CVSS 9.8) affecting papercut mf, papercut ng, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Critical severity
- EPSS top 1%: very likely to be exploited
- Exploited in the wild (CISA KEV)
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 85.6% (top 1%) |
| CISA exploited list | Yes, fix due 2026-09-14 |
| Weakness | CWE-305 |
| Published | 2026-08-28 |
| Last modified | 2026-09-14 |
Am I affected?
Timeline
- Published CVE record published
- Exploited Added to the CISA Known Exploited Vulnerabilities list
- Deadline CISA due date for US federal agencies to patch
- Updated Record last modified
papercut papercut mf UPGRADE
Affected: < 24.1.9 · >= 25.0.2 and < 25.0.12 · >= 26.0.2 and < 26.0.4
Fixed in: 24.1.9, 25.0.12, 26.0.4
Safe to downgrade to: a release before 25.0.2
1. Check installed version
apt-cache policy papercut-mf || rpm -q papercut-mf || papercut-mf --version
2. UPGRADE to 24.1.9 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade papercut-mf
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade papercut-mf
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 25.0.2 (Debian / Ubuntu)
apt-cache madison papercut-mf
sudo apt install papercut-mf=<VERSION_BEFORE_25.0.2>
sudo apt-mark hold papercut-mf
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list papercut-mf
sudo dnf downgrade papercut-mf-<VERSION_BEFORE_25.0.2>
sudo dnf versionlock add papercut-mf
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
papercut papercut ng UPGRADE
Affected: < 24.1.9 · >= 25.0.2 and < 25.0.12 · >= 26.0.2 and < 26.0.4
Fixed in: 24.1.9, 25.0.12, 26.0.4
Safe to downgrade to: a release before 25.0.2
1. Check installed version
apt-cache policy papercut-ng || rpm -q papercut-ng || papercut-ng --version
2. UPGRADE to 24.1.9 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade papercut-ng
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade papercut-ng
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 25.0.2 (Debian / Ubuntu)
apt-cache madison papercut-ng
sudo apt install papercut-ng=<VERSION_BEFORE_25.0.2>
sudo apt-mark hold papercut-ng
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list papercut-ng
sudo dnf downgrade papercut-ng-<VERSION_BEFORE_25.0.2>
sudo dnf versionlock add papercut-ng
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Exact fixes by distribution
Fedora 46 · uv · FIXED · 0.13.5-1.fc46 · FEDORA-2026-61ea5a28c6 · source
sudo dnf upgrade --advisory=FEDORA-2026-61ea5a28c6
Public exploits and detection
Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.
- GitHub PoC: yora1928/PaperCut-CVE-2026-81578-82078 (4 stars)
- GitHub PoC: virologi-info/papercut-toolkit (2 stars)
- Metasploit: PaperCut NG/MF Unauthenticated RCE (CVE-2026-81578 + CVE-2026-82078)
- Nuclei scan template: PaperCut NG/MF <=26.0.4 - Unauthenticated ConfigEditor Access via Tapestry Complex-Direct
Advisories and coverage
Research and news
- watchTowr Labs: Death By A Thousand PaperCuts (PaperCut Pre-Auth RCE Chain and Patch Bypasses WT-2026-0141-0144/CVE-2026-82077/CVE-2026-82078/CVE-2026-81578 2026-10-09
Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Related CVEs
- CVE-2026-82078 CRITICAL 9.1 EXPLOITED UPGRADE UPGRADE PaperCut NG/MF Unsafe Reflection Vulnerability