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CVE-2026-39843

Plane server-side request forgery (SSRF)

7.7 HIGHPublic exploitEPSS 0.35%
  1. Published9 Apr 2026

Description

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityNone
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Affected products

Plane≥ 0.28.0 < 1.3.0

Remediation

Fixed in
Plane≥ 1.3.0

References

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Frequently asked

Is CVE-2026-39843 being actively exploited?

CVE-2026-39843 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.35%.

How severe is CVE-2026-39843?

CVE-2026-39843 has a CVSS 3.1 base score of 7.7, rated high. EPSS estimates a 0.35% probability of exploitation.

Which products are affected by CVE-2026-39843?

Affected products include Plane.

How do I fix CVE-2026-39843?

Upgrade affected software to a fixed version, for example Plane 1.3.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-39843 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.