CVE-2026-43890 (GCVE-0-2026-43890)

Vulnerability from cvelistv5 – Published: 2026-05-11 21:09 – Updated: 2026-05-13 14:39
VLAI?
Title
Outline: IDOR in subscriptions.create allows cross-tenant subscription on private documents (sibling of GHSA-23jj-rp48-w7q7)
Summary
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.
Severity ?
7.7 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
CWE
  • CWE-639 - Authorization Bypass Through User-Controlled Key
Assigner
References
Impacted products
Vendor Product Version
outline outline Affected: >= 0.82.1, < 1.7.1
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.