CVE-2026-35208: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in lichess-org lila
CVE-2026-35208 is a cross-site scripting (XSS) vulnerability in the lichess-org lila platform. Approved streamers can inject arbitrary HTML into the /streamer page and the homepage Live streams widget by placing markup in their Twitch or YouTube stream title. Although a Content Security Policy (CSP) blocks inline script execution, the vulnerability still allows server-side HTML injection. To become an approved streamer, an account must be older than 2 days with at least 15 games or be verified/titled, and then receive moderator approval. The vulnerability affects versions prior to commit 0d5002696ae705e1888bf77de107c73de57bb1b3 and has a CVSS 4. 0 score of 5. 3 (medium severity).
AI Analysis
Technical Summary
This vulnerability involves improper neutralization of input during web page generation (CWE-79) in lichess-org's lila product. Specifically, approved streamers can inject arbitrary HTML content into the /streamer page and the Live streams widget on the homepage by embedding markup in their Twitch or YouTube stream titles. The platform fetches and renders these titles as-is once the streamer is approved and live, without additional sanitization. While a Content Security Policy is in place to block inline script execution, the server-side HTML injection remains a risk. The vulnerability requires only normal streamer privileges, which are granted after meeting minimal account age and activity criteria and moderator approval. The issue is fixed in commit 0d5002696ae705e1888bf77de107c73de57bb1b3.
Potential Impact
The vulnerability allows approved streamers to inject arbitrary HTML into parts of the lichess.org UI, potentially affecting users who view the Live streams widget or streamer pages. Although inline scripts are blocked by CSP, the HTML injection could still be used for UI manipulation or other attacks that do not require script execution. No elevated privileges beyond approved streamer status are needed to exploit this. There are no known exploits in the wild at this time.
Mitigation Recommendations
This vulnerability is fixed in commit 0d5002696ae705e1888bf77de107c73de57bb1b3. Users and administrators should update to this commit or a later version to remediate the issue. Since this is not a cloud service, patching the affected software version is required. No additional mitigation is indicated by the vendor advisory.
CVE-2026-35208: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in lichess-org lila
Description
CVE-2026-35208 is a cross-site scripting (XSS) vulnerability in the lichess-org lila platform. Approved streamers can inject arbitrary HTML into the /streamer page and the homepage Live streams widget by placing markup in their Twitch or YouTube stream title. Although a Content Security Policy (CSP) blocks inline script execution, the vulnerability still allows server-side HTML injection. To become an approved streamer, an account must be older than 2 days with at least 15 games or be verified/titled, and then receive moderator approval. The vulnerability affects versions prior to commit 0d5002696ae705e1888bf77de107c73de57bb1b3 and has a CVSS 4. 0 score of 5. 3 (medium severity).
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves improper neutralization of input during web page generation (CWE-79) in lichess-org's lila product. Specifically, approved streamers can inject arbitrary HTML content into the /streamer page and the Live streams widget on the homepage by embedding markup in their Twitch or YouTube stream titles. The platform fetches and renders these titles as-is once the streamer is approved and live, without additional sanitization. While a Content Security Policy is in place to block inline script execution, the server-side HTML injection remains a risk. The vulnerability requires only normal streamer privileges, which are granted after meeting minimal account age and activity criteria and moderator approval. The issue is fixed in commit 0d5002696ae705e1888bf77de107c73de57bb1b3.
Potential Impact
The vulnerability allows approved streamers to inject arbitrary HTML into parts of the lichess.org UI, potentially affecting users who view the Live streams widget or streamer pages. Although inline scripts are blocked by CSP, the HTML injection could still be used for UI manipulation or other attacks that do not require script execution. No elevated privileges beyond approved streamer status are needed to exploit this. There are no known exploits in the wild at this time.
Mitigation Recommendations
This vulnerability is fixed in commit 0d5002696ae705e1888bf77de107c73de57bb1b3. Users and administrators should update to this commit or a later version to remediate the issue. Since this is not a cloud service, patching the affected software version is required. No additional mitigation is indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-01T18:48:58.937Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d417e60a160ebd92da7f7c
Added to database: 4/6/2026, 8:30:30 PM
Last enriched: 4/14/2026, 4:00:23 PM
Last updated: 5/22/2026, 2:44:44 PM
Views: 40
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