CVE-2026-35208
lichess.org has an Unsanitized Stream Title Injection on /streamer
Description
lichess.org is the forever free, adless and open source chess server. Any approved streamer can inject arbitrary HTML into /streamer and the homepage “Live streams” widget by placing markup in their Twitch/YouTube stream title. CSP is present and blocks inline script execution, but the issue is still a server-side HTML injection sink. To trigger this, a Lichess account only needs to satisfy the normal streamer requirements and get approved. Per Streamer.canApply, that means an account older than 2 days with at least 15 games, or a verified/titled account. After moderator approval, once the streamer goes live, Lichess pulls the platform title and renders it into the UI as-is. No extra privileges are needed beyond a normal approved streamer profile. This vulnerability is fixed with commit 0d5002696ae705e1888bf77de107c73de57bb1b3.
INFO
Published Date :
April 6, 2026, 9:16 p.m.
Last Modified :
July 24, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update to the latest version of the software.
- Apply commit 0d5002696ae705e1888bf77de107c73de57bb1b3.
- Review streamer title input validation.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-35208.
| URL | Resource |
|---|---|
| https://github.com/lichess-org/lila/commit/0d5002696ae705e1888bf77de107c73de57bb1b3 | Patch |
| https://github.com/lichess-org/lila/security/advisories/GHSA-v7gh-939r-pfjq | Exploit Vendor Advisory |
| https://vimeo.com/1175908262 | Exploit |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-35208 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-35208
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-35208 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-35208 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Translation Title: lila de lichess-org, Description: lichess.org es el servidor de ajedrez para siempre gratuito, sin anuncios y de código abierto. Cualquier streamer aprobado puede inyectar HTML arbitrario en /streamer y el widget 'Live streams' de la página de inicio colocando marcado en el título de su transmisión de Twitch/YouTube. CSP está presente y bloquea la ejecución de scripts en línea, pero el problema sigue siendo un sumidero de inyección de HTML del lado del servidor. Para activar esto, una cuenta de Lichess solo necesita satisfacer los requisitos normales de streamer y ser aprobada. Según Streamer.canApply, eso significa una cuenta con más de 2 días de antigüedad con al menos 15 partidas, o una cuenta verificada/con título. Después de la aprobación del moderador, una vez que el streamer se conecta en vivo, Lichess extrae el título de la plataforma y lo renderiza en la interfaz de usuario tal cual. No se necesitan privilegios adicionales más allá de un perfil de streamer aprobado normal. Esta vulnerabilidad se corrige con el commit 0d5002696ae705e1888bf77de107c73de57bb1b3. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'lichess-org', 'product': 'lila', 'versions': [{'status': 'affected', 'version': '< 0d5002696ae705e1888bf77de107c73de57bb1b3'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-35208', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-04-07T14:55:58.549189Z'} -
Initial Analysis by [email protected]
Apr. 16, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:lichess:lila:*:*:*:*:*:*:*:* versions up to (excluding) 2026-03-31 Added Reference Type GitHub, Inc.: https://github.com/lichess-org/lila/commit/0d5002696ae705e1888bf77de107c73de57bb1b3 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/lichess-org/lila/security/advisories/GHSA-v7gh-939r-pfjq Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://vimeo.com/1175908262 Types: Exploit -
New CVE Received by [email protected]
Apr. 06, 2026
Action Type Old Value New Value Added Description lichess.org is the forever free, adless and open source chess server. Any approved streamer can inject arbitrary HTML into /streamer and the homepage “Live streams” widget by placing markup in their Twitch/YouTube stream title. CSP is present and blocks inline script execution, but the issue is still a server-side HTML injection sink. To trigger this, a Lichess account only needs to satisfy the normal streamer requirements and get approved. Per Streamer.canApply, that means an account older than 2 days with at least 15 games, or a verified/titled account. After moderator approval, once the streamer goes live, Lichess pulls the platform title and renders it into the UI as-is. No extra privileges are needed beyond a normal approved streamer profile. This vulnerability is fixed with commit 0d5002696ae705e1888bf77de107c73de57bb1b3. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-79 Added CWE CWE-116 Added Reference https://github.com/lichess-org/lila/commit/0d5002696ae705e1888bf77de107c73de57bb1b3 Added Reference https://github.com/lichess-org/lila/security/advisories/GHSA-v7gh-939r-pfjq Added Reference https://vimeo.com/1175908262