CVE-2026-42553— Cinny: Access token disclosure via invalidated emoji pack avatar URL in service worker

Cinny: Access token disclosure via invalidated emoji pack avatar URL in service worker

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.

N/A

输入验证不恰当

Cinny 输入验证错误漏洞

Cinny是Cinny开源的一款简洁安全的即时通讯客户端。 Cinny 4.10.3之前版本存在输入验证错误漏洞，该漏洞源于EmojiBoard使用不受信任的pack.meta.avatar作为URL且未验证，以及服务工作者未验证请求主机，可能导致远程认证攻击者窃取受害者Matrix访问令牌。

N/A

N/A