CVE-2026-43890
7.7 · HIGHOverview
CVE-2026-43890 is a high-severity vulnerability. It was published on May 11, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical Description
Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.7.0, the subscriptions.create API endpoint in server/routes/api/subscriptions/subscriptions.ts exhibits a broken authorization pattern. When both collectionId and documentId are supplied in the request, the route handler authorizes ONLY the collection branch (line 125 if (collectionId)), while the downstream subscriptionCreator command at server/commands/subscriptionCreator.ts writes the subscription against the documentId (which was never validated). The result is a subscription record pinning the attacker's user to a victim document the attacker has no read access to, on any team in the instance. The schema (server/routes/api/subscriptions/schema.ts) only enforces "at least one of collectionId/documentId" via .refine() — it does NOT enforce mutual exclusivity, so passing both is a valid, schema-conforming request. This vulnerability is fixed in 1.7.1.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Frequently Asked Questions
What is CVE-2026-43890?
CVE-2026-43890 is a high-severity vulnerability. It was published on May 11, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).
How severe is CVE-2026-43890?
This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-43890?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-43890?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-43890 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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