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CVE-2026-103858

MISP Incomplete Thread Authorization Allows Unauthorized Read and Post Access to Discussions

MISP MISP
Open in ThreatlineRecord JSON
CVSS
5.3Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.22%Chance of exploitation activity in the next 30 days, higher than 11% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in2.5.48Fixed versionCVE List
Published1 Oct 2026Updated 1 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

MISP contains an incomplete authorization check in the discussion posting functionality. When a user submits a post to a thread or replies to an existing post, the application only verified whether the target thread was restricted to a single organization (org-only distribution). It did not enforce the full thread access control list, including sharing-group membership and event-level visibility.

As a result, an authenticated user who is outside the relevant sharing group or who does not have visibility on the associated event could:

  • Read the thread title and the content of the quoted post
  • Submit a new post into the discussion thread

This constitutes both an information disclosure (reading restricted thread and post content) and an integrity issue (injecting content into a thread the user is not authorized to participate in).

Affected: <2.5.48

Text from CVE List

Affected versions 1

  • MISPaffected: unspecified before 2.5.48CVE List

References 1