CVE-2026-43888: Outline is a service that allows for collaborative documentation. Prior to 1.7.0, ZipHelper.extract computes the extraction path for each entry by pas...

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.

Metrics

CVSS 3.1

8.7/10

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

EPSS Probability

0.37%

28.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-22

References

Timeline

Published: May 11, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-43888?

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.

How severe is CVE-2026-43888?

CVE-2026-43888 has a CVSS score of 8.7/10 (HIGH severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2026-43888?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.