# Opencast: Stored XSS in Paella player via WebVTT/DFXP caption cue text

Advisory record · `GHSA-m6c8-jcw2-5r25`

- **Identifiers:** `GHSA-m6c8-jcw2-5r25` · `CVE-2026-77615`
- **State:** Confirmed
- **Severity:** CVSS 8.7 High
- **Critical:** No
- **Weakness (CWE):** [CWE-79](https://cwe.mitre.org/data/definitions/79.html)
- **Tags:** [Cross-site scripting (XSS)](https://agentprime.io/advisories/tag/xss.md)
- **Published:** 18 Sept 2026
- **Updated:** 18 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 18 Sept 2026, 13:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `org.opencastproject:opencast-engage-paella-player-7` (Maven): affected `<19.7 || >=20.0, <20.2`; fixed in `19.7`, `20.2`
- `paella-core` (npm): affected `<1.50.6`; fixed in `1.50.6`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 8.7 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0056, the 46th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 18 Sept 2026. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-m6c8-jcw2-5r25](https://github.com/advisories/GHSA-m6c8-jcw2-5r25)
- [OSV: GHSA-m6c8-jcw2-5r25](https://osv.dev/vulnerability/GHSA-m6c8-jcw2-5r25)
- <https://github.com/opencast/opencast/security/advisories/GHSA-m6c8-jcw2-5r25>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-77615>
- <https://github.com/opencast/opencast/pull/7736>
- <https://github.com/opencast/opencast/commit/701682c635f668228c3e8fb7b4564b3294788e40>
- <https://github.com/polimediaupv/paella-core/commit/94a36490808ac5a1f60a0745d71ec9253f6d206b>
- <https://github.com/polimediaupv/paella-core/commit/9b2f14ec4cf55efaf4c045c77a5ed8f5ec559ab4>
- <https://github.com/polimediaupv/paella-player/commit/6fe4af7306044198c8e91e2e7f4128428b83cf03>
- <https://github.com/opencast/opencast>
- <https://github.com/opencast/opencast/releases/tag/19.7>
- <https://github.com/opencast/opencast/releases/tag/20.2>
- <https://github.com/polimediaupv/paella-player/blob/a1b6c42467938a00a4b4d0b8c68435cd4f9d2a16/repos/paella-core/CHANGELOG.md?plain=1#L21>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-m6c8-jcw2-5r25>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-m6c8-jcw2-5r25/>. Everything for agents: <https://agentprime.io/llms.txt>.