What is CVE-2026-86174?

CVE-2026-86174 is a medium-severity vulnerability in Makeplane Plane, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-05.

How severe is CVE-2026-86174?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Auth bypass in Makeplane Plane

CVE-2026-86174

Plane through 1.4.2 fails to validate that issues belong to the deploy board's project in the public comment endpoint. Authenticated attackers can post comments to arbitrary issues across workspaces by supplying an issue_id parameter to the public deploy-board comment endpoint.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2026-09-05 · last modified 2026-09-16.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.7th percentile), scored 2026-10-22.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Makeplane Plane

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

github.com/makeplane/plane (product)
IssueCommentPublicViewSet.create (technical-description)
GitHub Issue #9441 (issue-tracking)
VulnCheck Advisory: Plane through 1.4.2 Arbitrary Comment Write via Public Deploy Board (third-party-advisory)

Frequently asked questions

What is CVE-2026-86174?: CVE-2026-86174 is a medium-severity vulnerability in Makeplane Plane, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-05.
How severe is CVE-2026-86174?: Medium severity. CVSS v3 base score is 4.3 out of 10.