Quick answers
- Is CVE-2026-86271 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-86271 being exploited in the wild.
- How severe is CVE-2026-86271?
- Medium severity, with a CVSS score of 4.7, published 7 September 2026.
- Which products and versions are affected?
- Fluentcms up to 0.0.5.
- Is there a fix for CVE-2026-86271?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-86271 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-86271?
- Check whether you run Fluentcms at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a cross-tenant authorization bypass in the PermissionManager.HasAccess() method and related File/Folder services. The root cause is improper caching: authorization data (user roles, roles, permissions) is fetched for one site and cached using null-coalescing operators (??=), then reused without revalidation when evaluating subsequent sites. Additionally, FolderService and FileService access objects by UUID without validating that the requesting user has authorization for the object's owning site. An authenticated administrator restricted to Site A can enumerate Site B, supply a Site B folder UUID to the File Management API, and read, upload, or modify Site B assets. The attack requires valid authentication but no special privileges beyond admin access to a single site.
Affected products
- FluentCMS FluentCMS up to 0.0.5
Timeline
- 2026-07-25: disclosed: Issue #2409 opened by researcher
- 2026-09-07: advisory: CVE-2026-86271 published