{"id":"CVE-2026-42553","revision":null,"records":[{"revision":"9cd67a11038c4ce5a4c96a5ba22862f9","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-42553","aliases":[],"title":"Cinny: Access token disclosure via invalidated emoji pack avatar URL in service worker","description":"Cinny is a Matrix client. Prior to 4.10.3, A 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. This is caused by 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. Also, 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). This vulnerability is fixed in 4.10.3.","state":0,"publishedAt":"2026-05-27T17:27:26.74+00:00","modifiedAt":"2026-05-27T18:01:39.578+00:00","affected":[{"ecosystem":"Vendor product","name":"cinny","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"cinnyapp\",\n                    \"product\": \"cinny\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 4.10.3\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","score":7.1,"severity":"HIGH"}],"references":["https://github.com/cinnyapp/cinny/security/advisories/GHSA-j944-w549-3453","https://github.com/cinnyapp/cinny/releases/tag/v4.10.3"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-42553","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-42553","identifiers":["CVE-2026-42553"]},"retained":false,"historicalAffected":[]},{"revision":"d6b431ab10f9408e8eadd62fbcda4965","observedAt":"2026-11-07T09:35:15.824+00:00","statement":{"source":"euvd","id":"EUVD-2026-32612","aliases":["CVE-2026-42553","GHSA-j944-w549-3453"],"title":"Cinny is a Matrix client. Prior to 4.10.3, A 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…","description":"Cinny is a Matrix client. Prior to 4.10.3, A 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. This is caused by 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. Also, 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). This vulnerability is fixed in 4.10.3.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","score":7.1,"severity":null}],"references":["https://github.com/cinnyapp/cinny/security/advisories/GHSA-j944-w549-3453","https://github.com/cinnyapp/cinny/releases/tag/v4.10.3"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-32612","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"May 27, 2026, 5:27:26 PM","dateUpdated":"May 27, 2026, 6:01:39 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-32612","identifiers":["EUVD-2026-32612","CVE-2026-42553","GHSA-j944-w549-3453"]},"retained":false,"historicalAffected":[]},{"revision":"aabe0cb5668343a785e3167fb3f2e347","observedAt":"2026-10-27T11:12:04.713+00:00","statement":{"source":"nvd","id":"CVE-2026-42553","aliases":[],"title":"Cinny is a Matrix client. Prior to 4.10.3, A 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…","description":"Cinny is a Matrix client. Prior to 4.10.3, A 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. This is caused by 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. Also, 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). This vulnerability is fixed in 4.10.3.","state":0,"publishedAt":"2026-05-27T18:16:22.857+00:00","modifiedAt":"2026-10-26T11:10:00.157+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":7.1,"severity":"HIGH"}],"references":["https://github.com/cinnyapp/cinny/releases/tag/v4.10.3","https://github.com/cinnyapp/cinny/security/advisories/GHSA-j944-w549-3453"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-42553","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-20"],"productCriteria":[],"sourceDates":{"published":"2026-05-27T18:16:22.857","lastModified":"2026-10-26T11:10:00.157"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-42553","identifiers":["CVE-2026-42553"]},"retained":false,"historicalAffected":[]},{"revision":"f065706511424a418df91db7cbd86442","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-j944-w549-3453","aliases":["CVE-2026-42553"],"title":"Cinny vulnerable to access token disclosure via invalidated emoji pack avatar URL in service worker","description":"### 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://github.com/cinnyapp/cinny/releases/tag/v4.10.3","state":0,"publishedAt":"2026-05-07T16:40:52+00:00","modifiedAt":"2026-06-09T00:00:19.3937404+00:00","affected":[{"ecosystem":"npm","name":"cinny","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"4.10.3"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/cinnyapp/cinny/security/advisories/GHSA-j944-w549-3453","https://nvd.nist.gov/vuln/detail/CVE-2026-42553","https://github.com/cinnyapp/cinny","https://github.com/cinnyapp/cinny/releases/tag/v4.10.3"],"sourceUrl":"https://github.com/advisories/GHSA-j944-w549-3453","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-j944-w549-3453","identifiers":["GHSA-j944-w549-3453","CVE-2026-42553"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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