CVE-2026-104979: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in makeplane plane
Description
Plane is an open-source project management tool. Prior to 1.4.0, IntakeIssuePublicViewSet.create in Plane v1.3.1 writes description_html through Issue.objects.create(...) without calling validate_html_content from nh3. Any authenticated user, including a new user with no workspace memberships, can plant arbitrary HTML in a project that has a published DeployBoard with intake enabled. When a project member or viewer of a closed intake item clicks the planted link, the TipTap \tjavascript: parser bypass and the target="_self" click handler execute JavaScript in the viewer's session and exfiltrate a long-lived API token. This issue is fixed in 1.4.0.
CVSS v3.1
Score 8.7high
Affected software
makeplane
plane
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Plane versions prior to 1.4.0 contain an XSS vulnerability in the IntakeIssuePublicViewSet.create function, which writes description_html without proper validation via validate_html_content. This allows authenticated users, even those without workspace memberships, to inject arbitrary HTML into projects with a published DeployBoard and intake enabled. The vulnerability exploits a TipTap JavaScript parser bypass and a target="_self" click handler to execute JavaScript in the victim's session, leading to exfiltration of a long-lived API token. The issue is resolved in Plane 1.4.0.
Potential Impact
Successful exploitation allows an attacker with authenticated access to inject malicious HTML that executes JavaScript in other users' sessions, leading to the theft of long-lived API tokens. This compromises confidentiality and integrity of user sessions and potentially the entire project environment. The vulnerability requires user interaction (clicking a malicious link) and affects users who view closed intake items in affected projects.
Mitigation Recommendations
Upgrade Plane to version 1.4.0 or later, where this vulnerability is fixed. No other mitigations are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-10-02T18:16:13.629Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ac3e69d2cdf04f65628b484
Added to database: 10/05/2026, 18:04:13 UTC
Last enriched: 10/05/2026, 18:18:32 UTC
Last updated: 10/05/2026, 19:34:03 UTC
Views: 10
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