What’s Vulnerable › Vulnerabilities

CVE-2025-58351: Outline's Local File Storage Feature can Cause CSP Bypass

• Severity: medium (CVSS 6.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-09-03 · updated 2026-10-19
• Weakness: CWE-79

Description

Outline is a service that allows for collaborative documentation. In versions 0.72.0 through 0.83.0, Outline introduced a feature which facilitates local file system storage capabilities as an optional file storage strategy. This feature allowed a CSP bypass as well as a ContentType bypass that might facilitate further attacks. In the case of self-hosting and using Outline FILE_STORAGE=local on the same domain as the Outline application, a malicious payload can be uploaded as a file attachment and bypass those CSP restrictions, allowing script execution within the context of another user. This is fixed in version 0.84.0.

Affected products

• outline: from 0.72.0 before 0.84.0 — fixed in 0.84.0

How to fix

Upgrade to a fixed version: outline 0.84.0. Check the vendor advisory for mitigations.

References

• https://github.com/outline/outline/commit/18bc93c9c207329244c6909606a2393e863892a3
• https://github.com/outline/outline/releases/tag/v0.84.0
• https://github.com/outline/outline/security/advisories/GHSA-gcj7-c9jv-fhgf

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