vulnerability / NVI-00014129 / Revision 1
Opencast: Stored XSS in Paella player via WebVTT/DFXP caption cue text
GitHub lists this reviewed advisory for org.opencastproject:opencast-engage-paella-player-7, org.opencastproject:opencast-engage-paella-player-7, paella-core. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.7 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
org.opencastproject:opencast-engage-paella-player-7
source listed< 19.7
## Summary The Opencast Paella player renders caption cue text into `innerHTML` without escaping. The captions canvas clears `_captionsContainer.innerHTML` and then appends each active cue with `_captionsContainer.innerHTML += cue`, so HTML inside a WebVTT or DFXP cue becomes live DOM and executes in the Opencast origin. The caption track is read from any media package element with a `captions/*` flavor and is served, with the player manifest, to anonymous viewers through `/search/episode.json`. The caption plugins that consume it are enabled in the default player configuration, the "Subtitles" upload that produces a `captions/source` track is active by default, and no caption processing step escapes the cue text. A user who can upload a subtitle to an event and publish it stores the payload in the published caption file. Any viewer who opens the event and turns captions on runs the script. Result: a non-admin content author stores JavaScript in a subtitle cue that executes in the browser session of every viewer who enables captions on that event, including anonymous viewers and authenticated staff. ## Affected opencast/opencast, `engage-paella-player` module. Supported relea
org.opencastproject:opencast-engage-paella-player-7
source listed>= 20.0, < 20.2
## Summary The Opencast Paella player renders caption cue text into `innerHTML` without escaping. The captions canvas clears `_captionsContainer.innerHTML` and then appends each active cue with `_captionsContainer.innerHTML += cue`, so HTML inside a WebVTT or DFXP cue becomes live DOM and executes in the Opencast origin. The caption track is read from any media package element with a `captions/*` flavor and is served, with the player manifest, to anonymous viewers through `/search/episode.json`. The caption plugins that consume it are enabled in the default player configuration, the "Subtitles" upload that produces a `captions/source` track is active by default, and no caption processing step escapes the cue text. A user who can upload a subtitle to an event and publish it stores the payload in the published caption file. Any viewer who opens the event and turns captions on runs the script. Result: a non-admin content author stores JavaScript in a subtitle cue that executes in the browser session of every viewer who enables captions on that event, including anonymous viewers and authenticated staff. ## Affected opencast/opencast, `engage-paella-player` module. Supported relea
paella-core
source listed< 1.50.6
## Summary The Opencast Paella player renders caption cue text into `innerHTML` without escaping. The captions canvas clears `_captionsContainer.innerHTML` and then appends each active cue with `_captionsContainer.innerHTML += cue`, so HTML inside a WebVTT or DFXP cue becomes live DOM and executes in the Opencast origin. The caption track is read from any media package element with a `captions/*` flavor and is served, with the player manifest, to anonymous viewers through `/search/episode.json`. The caption plugins that consume it are enabled in the default player configuration, the "Subtitles" upload that produces a `captions/source` track is active by default, and no caption processing step escapes the cue text. A user who can upload a subtitle to an event and publish it stores the payload in the published caption file. Any viewer who opens the event and turns captions on runs the script. Result: a non-admin content author stores JavaScript in a subtitle cue that executes in the browser session of every viewer who enables captions on that event, including anonymous viewers and authenticated staff. ## Affected opencast/opencast, `engage-paella-player` module. Supported relea
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-m6c8-jcw2-5r25 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.