What is CVE-2026-39843?

CVE-2026-39843 is a high-severity vulnerability in Makeplane Plane, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.7/10. Published 2026-04-09.

How severe is CVE-2026-39843?

High severity. CVSS v3 base score is 7.7 out of 10.

SSRF in Makeplane Plane

CVE-2026-39843

Plane is an an open-source project management tool. From 0.28.0 to before 1.3.0, the remediation of GHSA-jcc6-f9v6-f7jw is incomplete which could lead to the same full read Server-Side Request Forgery when a normal html page contains a link tag with an href that redirects to a private IP address is supplied to Add link by an authenticated attacker with low privileges. Redirects for the main page URL are validated, but not the favicon fetch path. fetch_and_encode_favicon() still uses requests.get(favicon_url, ...) with the default redirect-following. This vulnerability is fixed in 1.3.0.

Vulnerability class: SSRF (Server-Side Request Forgery)

Published 2026-04-09 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (26.3th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 26.3% 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: 0.004 · change: +0.001

Affected products

Makeplane Plane — versions >= 0.28.0, < 1.3.0
Plane

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

github.com/makeplane/plane/security/advisories/GHSA-9fr2-pprw-pp9j (Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-39843?: CVE-2026-39843 is a high-severity vulnerability in Makeplane Plane, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.7/10. Published 2026-04-09.
How severe is CVE-2026-39843?: High severity. CVSS v3 base score is 7.7 out of 10.