# CVE-2026-103858: MISP incomplete authorization check in discussion posting

Source: https://junglewise.ai/threats/cve-2026-103858-misp-contains-an-incomplete-authorization-check-in-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-01. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-103858 · Severity: info · Published 2026-10-01

MISP is an open-source threat intelligence sharing platform used by organizations to collaborate on security incidents and malware analysis. An authenticated user could bypass access controls on discussion threads to read restricted content and post messages into threads they should not have access to, compromising the confidentiality and integrity of sensitive threat intelligence discussions.

Technologies: [MISP Project MISP](https://junglewise.ai/threats/technologies/misp-project-misp). Vendors: [MISP Project](https://junglewise.ai/threats/vendors/misp-project).

## Quick answers

**Is CVE-2026-103858 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103858 being exploited in the wild.

**How severe is CVE-2026-103858?** Informational severity, published 1 October 2026.

**Which products and versions are affected?** MISP Project MISP prior to 2.5.48.

**Is there a fix for CVE-2026-103858?** Yes: fixed in 2.5.48. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-103858 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-103858?** Check whether you run MISP Project MISP 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.

## How to fix

- Fixed in 2.5.48

## Technical details

The discussion posting functionality in MISP performed incomplete authorization checks, verifying only whether a thread was restricted to a single organization but failing to enforce the full access control list including sharing-group membership and event-level visibility. An authenticated attacker with network access could read thread titles and quoted post content from restricted discussions and inject new posts into threads outside their authorized scope. The fix applies thread ACL checks to the posts/add endpoint.

## Affected products

- MISP Project MISP prior to 2.5.48

## Timeline

- 2026-10-01: disclosed

## References

- [https://github.com/MISP/MISP/commit/79fbd4c75](https://github.com/MISP/MISP/commit/79fbd4c75)

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