CVE-2026-61570 is a high-severity (CVSS 7.5) XML External Entity (XXE) vulnerability in net.sf.mpxj:mpxj. A fix is available for net.sf.mpxj:mpxj — see the affected versions and patch details below.
MPXJ: XXE Vulnerability in MerlinReader
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-61570.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-61570 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 384,189 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
net.sf.mpxj:mpxj.NETMPXJ.Net.NETnet.sf.mpxj.NETnet.sf.mpxj-for-csharp.NETnet.sf.mpxj-for-vb🐍mpxj💎mpxjReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven, NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Impact
MPXJ used the default configuration when creating a DocumentBuilder instance, which leaves doctype declarations enabled, when parsing the XML content of the ZTIMEINTERVALS column from a Merlin project SQLite file. This would allow a carefully crafted XML payload to read an arbitrary file. However, although an arbitrary file can be read, the way the resulting parsed XML is processed by MPXJ means that the data it contains is unlikely to be available for exfiltration.
Patches
The patch is included in MPXJ 16.4.1
Workarounds
Potential workarounds include:
- Avoid reading Merlin project files with MPXJ
- Only accept Merlin project files from trusted sources
- Preprocess Merlin SQLite databases to strip doctype declarations from the ZTIMEINTERVALS column
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | net.sf.mpxj:mpxj | ≥ 5.5.5&&< 16.4.1 | 16.4.1net.sf.mpxj:mpxj:16.4.1 |
| .NETNuGet | MPXJ.Net | ≥ 5.5.5&&< 16.4.1 | 16.4.1dotnet add package MPXJ.Net --version 16.4.1 |
| .NETNuGet | net.sf.mpxj | ≥ 5.5.5&&< 16.4.1 | 16.4.1dotnet add package net.sf.mpxj --version 16.4.1 |
| .NETNuGet | net.sf.mpxj-for-csharp | ≥ 5.5.5&&< 16.4.1 | 16.4.1dotnet add package net.sf.mpxj-for-csharp --version 16.4.1 |
| .NETNuGet | net.sf.mpxj-for-vb | ≥ 5.5.5&&< 16.4.1 | 16.4.1dotnet add package net.sf.mpxj-for-vb --version 16.4.1 |
| 🐍PyPI | mpxj | ≥ 5.5.5&&< 16.4.1 | 16.4.1pip install --upgrade 'mpxj==16.4.1' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for net.sf.mpxj:mpxj, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update net.sf.mpxj:mpxj to 16.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-61570 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-61570 in your dependencies?
Find it across Maven, NuGet, PyPI, including transitive dependencies.