CVE-2026-113611 outline CVE debrief

Who should care

Defenders responsible for Outline instances should assess exposure and prioritize remediation. This involves verifying the current version of Outline and upgrading to version 1.8.0 or later. Additionally, defenders should review webhook subscriptions and ensure that deleted administrators' subscriptions are properly disabled.

Why it matters

CVE-2026-113611 is an information disclosure vulnerability in Outline before version 1.8.0 that allows deleted administrators to continue receiving document contents via webhook subscriptions. Defenders should prioritize verifying exposure and remediating vulnerable instances.

• Verify exposure by assessing the current version of Outline in use.
• Remediate vulnerable instances by upgrading to version 1.8.0 or later.
• Review and disable webhook subscriptions for deleted administrators.

Technical summary

The vulnerability is caused by the UserDeletedProcessor not disabling webhook subscriptions for deleted administrators in Outline before version 1.8.0. This allows them to continue receiving full document bodies, including Markdown and Yjs data, for every matching workspace event. The issue was addressed in Outline version 1.8.0. Defenders should prioritize verifying exposure and remediating vulnerable Outline instances by assessing the current version of Outline in use and upgrading to version 1.8.0 or later. Additionally, defenders should review webhook subscriptions and ensure that deleted administrators' subscriptions are properly disabled.

Defensive priority

Defenders should prioritize verifying exposure and remediating vulnerable Outline instances. This involves assessing the current version of Outline in use and upgrading to version 1.8.0 or later. Additionally, defenders should review webhook subscriptions and ensure that deleted administrators' subscriptions are properly disabled.

Recommended defensive actions

• Verify the current version of Outline and upgrade to version 1.8.0 or later.
• Review webhook subscriptions and ensure that deleted administrators' subscriptions are properly disabled.
• Monitor for any suspicious activity related to webhook subscriptions and document access.
• Confirm whether affected Outline deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record and source item provide details about the vulnerability, including its description, affected versions, and references to vendor advisories and patches. However, the corpus does not provide information on exploitation or specific business impacts.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.