Bug 2430177 (CVE-2025-15265)

Summary: CVE-2025-15265 Svelte: Svelte: Remote script execution via Cross-Site Scripting (XSS) in async hydration
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Svelte. A remote attacker can exploit this Cross-Site Scripting (XSS) vulnerability during asynchronous hydration by providing specially crafted input. This input, when processed, allows for the injection of arbitrary JavaScript into a user's browser due to improper escaping of attacker-controlled keys within a script block. Successful exploitation can lead to remote script execution, potentially resulting in session theft and account compromise.
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2430305, 2430306    
Bug Blocks:    

Description OSIDB Bzimport 2026-01-15 21:03:29 UTC
An SSR XSS exists in async hydration when attacker‑controlled keys are passed to hydratable. The key is embedded inside a <script> block without HTML‑safe escaping, allowing </script> to terminate the script and inject arbitrary JavaScript. This enables remote script execution in users' browsers, with potential for session theft and account compromise.
This issue affects Svelte: from 5.46.0 before 5.46.3.