CVE-2025-63811 identifies a Denial-of-Service vulnerability in the jose2go library, versions 1.5.0 through 1.7.0, which is used for JSON Web Encryption (JWE) operations in Go applications. The vulnerability arises from the handling of JWE tokens that are compressed with an exceptionally high compression ratio. When such a crafted token is processed, the decompression step can consume excessive CPU and memory resources, leading to a resource exhaustion condition commonly known as a decompression bomb attack. This results in a Denial-of-Service (DoS) where the affected application becomes unresponsive or crashes. The flaw does not require authentication or user interaction, making it easier for remote attackers to exploit by sending maliciously crafted tokens to vulnerable endpoints. No CVSS score has been assigned yet, and no patches or fixes have been officially released. The vulnerability impacts the availability of services relying on jose2go for secure token handling, potentially disrupting authentication, authorization, or data exchange processes in web applications or APIs. The lack of known exploits in the wild suggests it is either newly discovered or not yet weaponized, but the risk remains significant due to the nature of the attack vector. Organizations using jose2go should assess their exposure and prepare mitigations to prevent exploitation.

For European organizations, exploitation of CVE-2025-63811 could lead to significant service disruptions in applications that rely on jose2go for JWE token processing. This includes web services, APIs, and authentication systems that use encrypted tokens for secure communication. A successful DoS attack could degrade availability, causing downtime or degraded user experience, potentially impacting business operations and customer trust. Confidentiality and integrity are less directly impacted, but availability loss can indirectly affect security posture and compliance with regulations such as GDPR, which mandates service reliability and data protection. Organizations in sectors with high reliance on secure token-based authentication, such as finance, healthcare, and government, may face operational risks and reputational damage. Additionally, the absence of patches means organizations must rely on mitigations and monitoring until a fix is available. The threat is heightened in environments where jose2go is widely deployed without additional protective controls.

To mitigate CVE-2025-63811, organizations should implement several specific measures: 1) Monitor and log the size and compression ratio of incoming JWE tokens to detect anomalous or suspicious inputs. 2) Enforce strict limits on the size and decompression resource usage for tokens, such as setting maximum decompressed size thresholds and timeouts on decompression operations. 3) Apply input validation to reject tokens that exceed expected size or compression parameters before processing. 4) Isolate the token processing component to limit the impact of potential DoS, for example by running it in a sandboxed environment or with resource quotas. 5) Stay updated with jose2go releases and apply patches promptly once available. 6) Consider alternative libraries or token handling mechanisms if jose2go usage is critical and no patch is available. 7) Employ Web Application Firewalls (WAFs) or API gateways capable of detecting and blocking malformed or oversized tokens. 8) Conduct regular security assessments and penetration testing focusing on token handling components to identify similar weaknesses.