Arch Linux Security Advisory ASA-202105-9 ========================================= Severity: High Date : 2021-05-19 CVE-ID : CVE-2021-29503 Package : hedgedoc Type : cross-site scripting Remote : Yes Link : https://security.archlinux.org/AVG-1946 Summary ======= The package hedgedoc before version 1.8.2-1 is vulnerable to cross-site scripting. Resolution ========== Upgrade to 1.8.2-1. # pacman -Syu "hedgedoc>=1.8.2-1" The problem has been fixed upstream in version 1.8.2. Workaround ========== In order to prevent unauthenticated attacks it can be useful to disable guest edits until the next update. To do this, set the following to configuration options: { # other configs # … "allowAnonymous": false, "allowAnonymousEdits": false, } Or set the environment variables CMD_ALLOW_ANONYMOUS=false and CMD_ALLOW_ANONYMOUS_EDITS=false. Description =========== HedgeDoc before version 1.8.2 is vulnerable to a cross-site scripting (XSS) attack using the YAML-metadata of a note. An attacker with write access to a note can embed HTML tags in the Open Graph metadata section of the note, resulting in the frontend rendering the script tag as part of the <head> section. This vulnerability affects all installations. Unless your instance prevents guests from editing notes, this vulnerability allows unauthenticated attackers to inject JavaScript into notes that allow guest edits. If your instance prevents guests from editing notes, this vulnerability allows authenticated attackers to inject JavaScript into any note pages they have write-access to. Impact ====== A remote attacker with write access to a note can inject arbitrary JavaScript code that is executed through cross-site scripting when the note is viewed. References ========== https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-gjg7-4j2h-94fq https://github.com/hedgedoc/hedgedoc/commit/4a0216096a6aa1ebba9d8b0ada067c73... https://security.archlinux.org/CVE-2021-29503