CVE-2026-46671 onenote.rs vulnerability
Rust OneNote File Parser is a parser for Microsoft OneNote files implemented in Rust. Prior to version 1.1.1, a maliciously crafted `.onetoc2` table-of-contents file can cause `Parser::parse_notebook` to open arbitrary files on the host filesystem outside the notebook's directory. The parser reads entry names listed inside the `.onetoc2` and joins them against the notebook's base directory without validating that they are relative paths confined to that directory. The parser will bail out when the target file fails to parse as a OneNote section, so direct content exfiltration through the parser's return value is not practical, though file-existence probing and denial-of-service via large or special files remain possible. Anyone using `onenote_parser` to parse .onetoc2 files received from untrusted sources is affected. Users who only ever parse their own notebooks are not at meaningful risk. The issue is fixed in onenote_parser 1.1.1. The fix rejects absolute paths, parent-directory components, and other invalid path characters in entry names, and additionally canonicalises the resolved path to confirm it stays inside the notebook's base directory. For users who cannot upgrade to 1.1.1, only call `Parser::parse_notebook` on `.onetoc2` files from trusted sources. Alternatively, use `Parser::parse_section` / `Parser::parse_section_buffer` on individual .one files, which do not perform the directory walk.
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msiemens onenote.rs should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- < 1.1.1
Fixed versions
- Apply the latest vendor-supported patched version.
How to fix it
CVE-2026-46671 affects onenote.rs and involves file access or path traversal. Successful exploitation may read, overwrite, or delete files outside the intended directory. Prioritize deployments that process untrusted input, expose the affected feature, or hold sensitive data. Upgrade onenote.rs to 1.1.1 or a later vendor-supported fixed release.
- Inventory every deployment, device, package, plugin, container, build, and environment that uses onenote.rs.
- Compare the installed version with the recorded affected range: < 1.1.1.
- Upgrade onenote.rs to 1.1.1 or a later vendor-supported fixed release.
- Until patched, reject absolute and parent-relative paths, confine filesystem access to an explicit root, and accept files or manifests only from trusted sources.
- Review configuration, roles, tokens, network paths, and exposed endpoints connected to onenote.rs; remove access that is not required.
- Review filesystem, application, and audit logs for parent-directory segments, absolute paths, unexpected reads, writes, or deletions outside the intended root.
- If exploitation is suspected, isolate affected assets, preserve evidence, rotate exposed credentials or keys, restore trusted data, and rebuild compromised systems before returning them to service.
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Verify the fix
- Confirm every affected asset now runs the fixed vendor-supported release or has the documented mitigation for CVE-2026-46671 in place.
- Use a safe regression test to confirm the affected file access or path traversal path no longer produces the vulnerable behavior.
- Confirm temporary access controls, endpoint restrictions, network blocks, and least-privilege settings remain effective after the update.
- Review post-remediation logs and rerun Fixnx plus the relevant package, dependency, firmware, browser, or product-specific security check.
- Document affected assets, versions, changes, validation evidence, reviewed logs, and any credential rotation, cleanup, or replacement completed.
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Trusted references
FAQ
What is affected by CVE-2026-46671?
msiemens onenote.rs versions listed as affected should be reviewed: < 1.1.1.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.