# CVE-2026-104979: Plane: Cross-tenant stored XSS in intake enables account takeover

> Authenticated users can inject malicious HTML into intake issues, leading to stored XSS and API token exfiltration when viewed by others.

- **Severity:** High 8.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 5 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** GHSA-hh2r-3hwp-mvq3

## What is CVE-2026-104979?

CVE-2026-104979 is a high-severity cross-site scripting vulnerability in makeplane plane, published on 5 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-862 (Missing Authorization), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-104979?


## How do I fix CVE-2026-104979?

No fix has been published for CVE-2026-104979 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104979 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104979 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104979 and fix it if it is affected.

What it is: CVE-2026-104979 is a high-severity cross-site scripting vulnerability in makeplane plane, published on 5 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104979 exists.

Affected product: makeplane plane. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-104979/ (Markdown: https://insights.sbomify.com/CVE-2026-104979/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104979
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104979
- OSV: https://osv.dev/vulnerability/CVE-2026-104979

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104979/
Summaries are generated and may contain mistakes; the official description above is the record.