CVE-2026-43888 Outline: Zip Extraction Path Escape via PATH_MAX Truncation in Collection Import
Attackers can write files outside the intended directory during zip import due to path truncation, potentially modifying system files.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-43888?
CVE-2026-43888 is a high-severity path traversal vulnerability in outline, published on 11 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
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.
Weakness: CWE-22
Which versions are affected by CVE-2026-43888?
How do I fix CVE-2026-43888?
No fix has been published for CVE-2026-43888 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-43888 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43888 exists.
Sources
Also known as GHSA-hw32-2v7j-mgqc.