CVE-2026-46671: msiemens onenote.rs Path Traversal

Vulnerability summary

CVE-2026-46671 is a medium (CVSS 4.4) Path Traversal vulnerability in msiemens onenote.rs. EPSS estimates a 0.15% chance of exploitation in the next 30 days, higher than 4% of scored vulnerabilities.

Timeline

1. 20-07-2026
   PublishedVulnerability first disclosed.
2. 20-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')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.