{"items":[{"id":"NVI-00018355","kind":"vulnerability","title":"Cinny vulnerable to access token disclosure via invalidated emoji pack avatar URL in service worker","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-j944-w549-3453","CVE-2026-42553"],"plain_summary":"GitHub lists this reviewed advisory for cinny. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-15ac59e9514bf05e088c27a5e9609766"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-15ac59e9514bf05e088c27a5e9609766","url":"https://github.com/advisories/GHSA-j944-w549-3453","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-j944-w549-3453","publisher":"GitHub Advisory Database","observed_at":"2026-11-07T00:50:36.189Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-15ac59e9514bf05e088c27a5e9609766"],"technology":"cinny","known_exclusions":[],"conditions_summary":"### Impact\nA remote authenticated attacker who shares a room with a victim and has permissions to create room emotes (for example in a DM) can cause the victim's client to send their Matrix access token to an attacker-controlled server. This occurs when the victim opens the emoji or sticker picker for the room containing a malicious emote pack. \n\nThe root causes are: \n\n(1) an incorrect fallback in EmojiBoard that uses untrusted `pack.meta.avatar` (user-controlled) without converting/validating it as an MXC URL, allowing arbitrary HTTP(S) URLs to be used; and \n\n(2) the service worker attaching the user's Authorization bearer token to all outbound GET requests whose URL contains `/_matrix/client/v1/media/download` or `/_matrix/client/v1/media/thumbnail` without verifying the request host matches the configured homeserver origin. An attacker-controlled URL containing those path fragments and permissive CORS will receive the victim's Authorization header (access token). \n\nImpacted users: anybody using affected Cinny web app versions who opens the emoji/sticker picker in a room containing a malicious emote pack and who is logged in (authenticated).\n\n### Patches\nVersion with fixes: https","public_affected_ranges":["< 4.10.3"]}],"null_published_at":"2026-11-07T07:07:39.822Z","source_updated_at":"2026-06-08T23:47:44.000Z","source_disclosed_at":"2026-05-07T16:40:52.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-07T00:50:36.189Z"}],"next_cursor":null,"snapshot_revision":"42594"}