CVE-2026-43888 HIGH

CVE-2026-43888: Outline: Zip Extraction Path Escape via PATH_MAX Truncation in Collection Import

Vendor Outline
Product outline
Weakness CWE-22 · Path traversal
Published May 11, 2026
Last update May 12, 2026

CVSS base score

8.7/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction None
Confidentiality None
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:H

What the vulnerability does

01Description

Outline is a service that allows for collaborative documentation. Prior to 1.7.0, ZipHelper.extract computes the extraction path for each entry by passing a full filesystem path through trimFileAndExt, a filename helper that calls path.basename on its input when truncating. When a zip entry's nested path is long enough to push the joined filesystem path over MAX_PATH_LENGTH (4096 bytes), trimFileAndExt silently drops all directory components and returns a bare filename. fs.createWriteStream then opens the file relative to the process working directory instead of inside the extraction sandbox, and the escaped file persists after import cleanup because cleanupExtractedData only removes the temporary extraction directory. This vulnerability is fixed in 1.7.0.

Key dates

02Disclosure timeline

May 11, 2026 CVE published
May 12, 2026 Record updated