msiemens onenote.rs up to 1.1.0 Parser Parser::parse_notebook path traversal

Summaryinfo

A vulnerability, which was classified as critical, has been found in msiemens onenote.rs up to 1.1.0. Affected by this vulnerability is the function Parser::parse_notebook of the component Parser. The manipulation leads to path traversal. This vulnerability is listed as CVE-2026-46671. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in msiemens onenote.rs up to 1.1.0 and classified as critical. This issue affects the function Parser::parse_notebook of the component Parser. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-46671 since 05/15/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 1.1.1 eliminates this vulnerability.

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Productinfo

Vendor

• msiemens

Name

• onenote.rs

Version

• 1.0
• 1.1.0

Website

• Product: https://github.com/msiemens/onenote.rs/

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