CVE-2026-81578
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PaperCut MF/NG: Authentication Bypass
rank 93 = 40 + 25 + 12 + 6 + 10
rank@v1 · act now
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.85169 · CISA KEV listed · without this subject the record ranks 53
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 9.8, from NVD · without this subject the record ranks 68
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
rose on 2026-09-30 · without this subject the record ranks 81
How much of the world it touches
NVD CPE configurations
6 products in the CPE ranges · without this subject the record ranks 87
Someone else already set the date
CISA KEV remediation due date
CISA remediation date held · without this subject the record ranks 83
$3.40M = $4.99M incident cost x 0.8004932139359172 exposure x 0.85169 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
This record is one instance of CWE-305, authentication bypass by primary weakness. The index holds 171 prior instances of this class, 2 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
Running PaperCut MF/NG? Check your version
A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Show full CISA 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). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Exploited in the wild · CISA KEV listed, 2026-08-31.
Affected & Fixed Versions as published
Show all 6 published ranges
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
What it is stated by the CNA
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. receipt
NVD's analysis a second authority
- severity
- 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- weakness
- CWE-305
- affected versions
- papercut mf < 24.1.9; papercut mf >= 25.0.2 < 25.0.12; papercut mf >= 26.0.2 < 26.0.4; and 3 more, listed in full below
- also scored by
- 8.8 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
The CNA scored it 8.8 and NVD 9.8. Both are shown because both were published; we do not pick one.
check it yourself papercut.com receipt
Dated events
Movement the material steps
This score more than doubled inside 72 hours. Both observations are in the full history below.
Show all 6 observations
6 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
Listed by CISA 3 days after it published, exploit probability more than doubled between 2026-09-01 and 2026-09-04 (0.00771 → 0.01617) and the record had been public for 1 month when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-305, authentication bypass by primary weakness. The index holds 171 prior instances of this class, 2 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]
"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1
171 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.
No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.
Siblings and hubs
Records related to this one
No record cites this identifier and it carries no alias. The advisory that covers it is below.
Fixed with these, by one advisory
security-bulletin-27-aug-2026-urgent-security-advisory
Of the 2 records in this advisory, this is the only one holding a CISA KEV listing: PaperCut NG/MF Missing Authentication for Critical Function .
Listed because one advisory covers them, not because they are the same defect. Each record's own state is on its own page.
Grouping: held values
Browse the index from here
These are index-wide views, not findings about CVE-2026-81578.
What usually comes next
Everything above needs no account. What is below is work: assembling it, scoping it to your estate, watching it, and handing it to someone else.