CVE-2026-50146: CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) in withastro astro
Astro, a web framework, has a reflected cross-site scripting (XSS) vulnerability in versions prior to 6.3.3. The issue occurs when a component uses a client:* directive, causing Astro to insert named slot content into a data-astro-template attribute without proper HTML escaping. This allows attackers to break out of the attribute context and inject arbitrary HTML during server-side rendering (SSR). The vulnerability is fixed in version 6.3.3.
AI Analysis
Technical Summary
CVE-2026-50146 describes a reflected XSS vulnerability in the Astro web framework. Specifically, before version 6.3.3, when a component uses a client:* directive, Astro inserts named slot content into a data-astro-template attribute without escaping the slot name. This improper neutralization of script-related HTML tags (CWE-80) enables an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected cross-site scripting during SSR. The vulnerability has a CVSS 3.1 score of 7.1 (high severity) and is fixed in Astro version 6.3.3.
Potential Impact
An attacker can exploit this vulnerability to inject arbitrary HTML into the server-side rendered page, potentially leading to reflected cross-site scripting attacks. This can result in the execution of malicious scripts in the context of the victim's browser, impacting confidentiality and integrity (CVSS impact: C:L, I:H, A:N). There are no known exploits in the wild at this time.
Mitigation Recommendations
This vulnerability is fixed in Astro version 6.3.3. Users should upgrade to version 6.3.3 or later to remediate this issue. No other mitigation or temporary workaround is indicated.
CVE-2026-50146: CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) in withastro astro
Description
Astro, a web framework, has a reflected cross-site scripting (XSS) vulnerability in versions prior to 6.3.3. The issue occurs when a component uses a client:* directive, causing Astro to insert named slot content into a data-astro-template attribute without proper HTML escaping. This allows attackers to break out of the attribute context and inject arbitrary HTML during server-side rendering (SSR). The vulnerability is fixed in version 6.3.3.
CVSS v3.1
Score 7.1high
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-50146 describes a reflected XSS vulnerability in the Astro web framework. Specifically, before version 6.3.3, when a component uses a client:* directive, Astro inserts named slot content into a data-astro-template attribute without escaping the slot name. This improper neutralization of script-related HTML tags (CWE-80) enables an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected cross-site scripting during SSR. The vulnerability has a CVSS 3.1 score of 7.1 (high severity) and is fixed in Astro version 6.3.3.
Potential Impact
An attacker can exploit this vulnerability to inject arbitrary HTML into the server-side rendered page, potentially leading to reflected cross-site scripting attacks. This can result in the execution of malicious scripts in the context of the victim's browser, impacting confidentiality and integrity (CVSS impact: C:L, I:H, A:N). There are no known exploits in the wild at this time.
Mitigation Recommendations
This vulnerability is fixed in Astro version 6.3.3. Users should upgrade to version 6.3.3 or later to remediate this issue. No other mitigation or temporary workaround is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-03T18:49:32.276Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a398861eed863c81e5021bb
Added to database: 06/22/2026, 19:09:21 UTC
Last enriched: 06/22/2026, 19:24:18 UTC
Last updated: 06/22/2026, 22:23:03 UTC
Views: 9
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.