VulnerabilityPublished 13 Nov 2025

CVE-2025-52186: Lichess lila · Server-Side Request Forgery (SSRF)

Source CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

To mitigate CVE-2025-52186, organizations should immediately update Lichess lila to the fixed version post commit 11b4c0fb00f0ffd823246f839627005459c8f05c once available. In the interim, implement strict input validation and sanitization on the 'players' parameter to ensure only expected and safe URLs or identifiers are accepted. Employ allowlisting for outbound HTTP requests initiated by the server, restricting them to known safe destinations. Network segmentation and firewall rules should be enforced to limit the server's ability to reach sensitive internal services. Monitoring and logging outbound HTTP requests from the Lichess server can help detect anomalous activity indicative of SSRF exploitation attempts. Additionally, consider deploying Web Application Firewalls (WAFs) with rules tailored to detect and block SSRF patterns. Regular security assessments and penetration testing focused on SSRF vectors are recommended to identify and remediate similar issues proactively.

Description

Lichess lila before commit 11b4c0fb00f0ffd823246f839627005459c8f05c (2025-06-02) contains a Server-Side Request Forgery (SSRF) vulnerability in the game export API. The players parameter is passed directly to an internal HTTP client without validation, allowing remote attackers to force the server to send HTTP requests to arbitrary URLs

Impact

For European organizations, the SSRF vulnerability in Lichess lila could lead to unauthorized internal network reconnaissance or access to sensitive internal services that are not exposed externally. This could result in partial confidentiality loss if internal endpoints return sensitive data or metadata. Additionally, attackers might leverage the SSRF to cause denial of service by overwhelming internal services or triggering unintended actions. Organizations hosting Lichess instances or integrating its APIs could see disruption or data leakage. Given the popularity of Lichess in Europe, particularly among educational institutions, chess clubs, and online communities, the risk extends to both private and public sector entities. The medium severity indicates that while the vulnerability is exploitable remotely without authentication, the impact is somewhat limited to confidentiality and availability, with no direct integrity compromise. However, SSRF can be a stepping stone for more complex attacks, especially if combined with other vulnerabilities or misconfigurations in internal networks.

CWE-918Server-Side Request Forgery (SSRF) (opens in a new tab)
Base weaknessCWE Top 25 (2025): #22OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.6.1 (opens in a new tab)
V5.2.6 (opens in a new tab)
Attack patterns
Server Side Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 20 Nov 2025, 16:18 UTC

WeaknessesCWE-918

Technical details

References

Community reviews

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