CVE-2026-82078
CVE-2026-82078 is a security flaw in PaperCut NG/MF, printing software offices and schools use. Attackers can run their own code on PaperCut NG/MF. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 31 Aug 2026.[1]
PaperCut NG/MF 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. Fixed in version 24.1.10, 25.0.13 and 26.0.5 of PaperCut MF/NG.
Description
CISA calls it an unsafe reflection in PaperCut NG/MF. In its words: “PaperCut NG/MF contains an unsafe reflection vulnerability that allows an attacker to manipulate system configuration parameters and execute arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process. This vulnerability can be chained with CVE-2026-81578.”[1]
The CVE record adds: “An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG. The application instantiates database driver classes based on configurable driver names without validating against an allowlist of approved drivers. If an attacker can manipulate system configuration parameters, this enables the execution of arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process.”[2]
The underlying weakness is CWE-470, in MITRE’s list of common software weaknesses.
It scores 9.1 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 lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| PaperCut MF/NG | 24.1.10 |
| PaperCut MF/NG | 25.0.13 |
| PaperCut MF/NG | 26.0.5 |
Most families won’t have PaperCut NG/MF; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 31 Aug 2026, 3 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 14 Sep 2026 to fix it.[1]
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 63%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
PaperCut has published a fix or advice.[3] CISA’s required action: “Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes).”[1]
- Check whether you use it.PaperCut NG/MF 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 (fixed in version 24.1.10, 25.0.13 and 26.0.5 of PaperCut MF/NG), or not in use. CISA gave US government agencies until 14 Sep 2026 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 9.1.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[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 63%.[4] |
See also
Other PaperCut NG/MF flaws
- CVE-2026-81578: missing authentication for critical function ·
- CVE-2023-27351: improper authentication ·
- CVE-2023-2533: cross-site request forgery (CSRF) ·
Other PaperCut flaws
- CVE-2023-27350, PaperCut MF/NG: improper access control ·
Added the same day
- CVE-2026-81578, PaperCut NG/MF: missing authentication for critical function ·
Every PaperCut flaw on CISA’s list · Everything added in August 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “PaperCut NG/MF Unsafe Reflection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 31 Aug 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-82078 Detail”. National Vulnerability Database, published 28 Aug 2026.
- ^ PaperCut. Advisories and fixes: papercut.com, papercut.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.630, percentile 99.2, 31 Oct 2026.
- CVE Program. “CVE-2026-82078”. 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.