CVE-2026-85533 MISP Sharing Group Authorization Bypass via Omitted Distribution Parameter
Authenticated users can bypass Sharing Group authorization checks by omitting the distribution parameter, allowing unauthorized data association with restricted groups.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-85533?
CVE-2026-85533 is a high-severity missing authorization vulnerability in misp, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
An authorization flaw in MISP allowed an authenticated user to submit a sharing_group_id without verifying that the user was authorized to use the referenced Sharing Group.
In several attribute and Galaxy Cluster creation and editing workflows, validation of the submitted Sharing Group was performed only when the request explicitly set the distribution field to 4 ("Sharing Group"). An attacker could therefore craft a request containing a sharing_group_id while omitting the distribution parameter, or otherwise avoiding the distribution == 4 condition, causing the Sharing Group authorization check to be skipped.
This could allow a user with permission to create or modify the affected MISP objects to associate data with a Sharing Group that they are not authorized to use. Depending on the affected object's existing distribution settings and subsequent processing, this could bypass intended information-sharing boundaries and result in unauthorized placement or distribution of data to members of another Sharing Group.
The issue affected attribute attachment and editing operations as well as Galaxy Cluster creation and editing. The fix ensures that authorization is performed whenever a non-empty sharing_group_id is submitted, independently of the distribution parameter. It also centralizes the authorization decision in SharingGroup::canUse() and explicitly rejects empty Sharing Group identifiers rather than allowing them to be interpreted as an unrestricted query.
Weakness: CWE-862
Which versions are affected by CVE-2026-85533?
How do I fix CVE-2026-85533?
No fix has been published for CVE-2026-85533 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-85533 being exploited?
There is no known exploitation of CVE-2026-85533 in the wild and no public exploit code.
Sources
Also known as GHSA-4pv3-xjc8-wfm8.