CVE-2025-51846 is a high-severity vulnerability affecting CryptPad 2025.3.1, which allows unbounded WebSocket frame flood. This vulnerability allows a remote, unauthenticated attacker to significantly degrade or deny service for all users of a CryptPad instance. The problem originates from improper handling of WebSocket connections, which can lead to resource exhaustion. Organizations using impacted versions of CryptPad should prioritize patching immediately.
The CVSS score for this vulnerability is 8.7, indicating a high severity level. With a low attack complexity and no required privileges or user interaction, the risk is considerable. Exploitation can lead to a complete denial of service, impacting the availability of CryptPad for all users. As such, organizations must act promptly to mitigate this risk.
The vulnerability was published on April 30, 2026, and it has been analyzed and confirmed to have no required privileges. Organizations using CryptPad should remain vigilant and ensure they have upgraded to version 2026.2.2 or later, which addresses this issue.
Organizations should also consider implementing additional security measures, such as rate limiting on WebSocket connections, to further protect against potential exploitation of this vulnerability.
Vulnerability Details
The official description for CVE-2025-51846 states that CryptPad 2025.3.1 allows unbounded WebSocket frame flood. As detailed, this vulnerability is categorized under CWE-770, which relates to improper handling of resource consumption. The CVSS 4.0 vector for this vulnerability is "CVSS:4.0/AV:N/AC:L/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X."
The affected product is CryptPad by xwiki, and the vulnerability impacts all versions from 2025.3.1 up to, but not including, 2026.2.2, which was released to address this issue.
Technical Analysis
The root cause of CVE-2025-51846 lies in the WebSocket handling mechanism of CryptPad, which fails to limit the number of incoming frames. This allows attackers to send a flood of WebSocket frames, overwhelming the server resources. The attack vector is network-based, and the complexity is low, meaning that attackers with minimal skill can exploit this vulnerability.
No privileges are required to exploit this vulnerability, and user interaction is not necessary. This makes the attack particularly dangerous as any unauthenticated individual could trigger the flood, leading to a significant impact on service availability.
The availability impact is classified as high, as the flood can deny service to all users of the CryptPad instance. Organizations should monitor their systems for unusual WebSocket activity to detect potential exploitation attempts.
Risk & Impact Analysis
Risk to organizations includes potential downtime and degraded service quality, which could lead to loss of user trust and operational disruptions. The blast radius of this vulnerability is extensive, affecting all users of a CryptPad instance. Given that the CVSS score is high, organizations should address this vulnerability in their priority patch cycle.
With the vulnerability confirmed and patches available, organizations should act swiftly to implement the necessary updates. The urgency for defenders is clear: patching is critical to maintaining service integrity and availability.
Organizations should also consider implementing additional security measures, such as rate limiting, to mitigate the risk of future exploitation. This layered approach will help reduce the attack surface and enhance overall security posture.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerable versions of CryptPad are from 2025.3.1 to 2026.2.1. Users should upgrade to version 2026.2.2 or later to mitigate the risk associated with this vulnerability.
Mitigation & Remediation
Organizations must patch their CryptPad installations to version 2026.2.2 immediately. This update addresses the WebSocket frame flood issue. If immediate patching is not possible, organizations should consider implementing rate limiting on WebSocket connections to control the frame flood issue.
For a complete guide on how to implement effective security testing, organizations can refer to the penetration testing methodologies that can help identify similar vulnerabilities.
Detection Guidance
Organizations should monitor their WebSocket connections for unusual activity patterns, such as a sudden increase in the number of frames being sent. Log analysis should focus on timestamps and IP addresses that may indicate potential flood attempts.
Additionally, behavioral anomalies in usage patterns can help identify exploitation attempts. Monitoring network traffic for spikes in WebSocket activity can also serve as an early warning sign.
AppSecure Threat Intelligence Insight
CVE-2025-51846 is significant not only due to its immediate impact but also because it highlights the importance of robust WebSocket handling in applications. This vulnerability represents a pattern where insufficient validation of WebSocket frames can lead to severe service disruptions.
Security teams should take this incident as a learning opportunity to fortify their WebSocket implementations and consider ongoing security assessments, such as API security testing, to ensure their systems are resilient against similar vulnerabilities.
Furthermore, organizations should regularly engage in penetration testing methodologies to identify and remediate vulnerabilities proactively.
In conclusion, the lessons learned from CVE-2025-51846 emphasize the need for continuous vigilance and improvement in security practices to mitigate risks associated with evolving threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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