CVE-2024-29370 is a vulnerability identified in the python-jose library version 3.3.0, specifically within the jwe.decrypt function responsible for decrypting JSON Web Encryption (JWE) tokens. The flaw arises when an attacker crafts a malicious JWE token that has an exceptionally high compression ratio. During the decryption process, the library attempts to decompress this token, which leads to excessive memory allocation and prolonged processing time. This behavior can overwhelm server resources, causing a Denial-of-Service (DoS) condition. The vulnerability is classified under CWE-409 (Improper Resource Shutdown or Release), indicating resource exhaustion issues. Exploitation requires no privileges or user interaction and can be performed remotely by sending the malicious token to a vulnerable service. The CVSS 3.1 base score is 5.3, reflecting a medium severity with the vector indicating network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability. No patches or fixes have been published at the time of this analysis, and no known exploits are reported in the wild. The vulnerability primarily affects applications that rely on python-jose 3.3.0 for secure token handling, especially those that accept JWE tokens from untrusted sources. The attack surface includes web APIs, authentication services, and other systems that decrypt JWE tokens as part of their workflow.

For European organizations, this vulnerability poses a risk of service disruption due to resource exhaustion when processing malicious JWE tokens. Organizations that use python-jose 3.3.0 in their authentication or API token handling mechanisms could experience degraded performance or outages, impacting availability of critical services. This could affect sectors such as finance, healthcare, government, and e-commerce, where secure token-based authentication is common. The DoS condition does not compromise confidentiality or integrity but can lead to denial of legitimate user access, potentially causing operational and reputational damage. Since the attack requires no authentication and can be launched remotely, the threat is significant for internet-facing services. The lack of known exploits in the wild reduces immediate risk, but the presence of a public CVE and medium severity score means attackers may develop exploits in the future. European organizations with high dependency on Python-based web frameworks and microservices architectures are particularly vulnerable.

1. Monitor python-jose project repositories and security advisories for official patches or updates addressing CVE-2024-29370 and apply them promptly once available. 2. Implement input validation and rate limiting on endpoints that accept JWE tokens to detect and block tokens with suspiciously high compression ratios or abnormal sizes. 3. Employ resource usage monitoring and set strict memory and CPU usage limits for services handling JWE decryption to prevent resource exhaustion. 4. Consider using alternative libraries or updated versions of python-jose that are not affected by this vulnerability if immediate patching is not possible. 5. Deploy Web Application Firewalls (WAFs) with custom rules to detect and block malformed or malicious JWE tokens. 6. Conduct security testing and fuzzing on token processing components to identify and mitigate similar resource exhaustion risks. 7. Educate development teams about secure handling of compressed data and the risks of decompression bombs. 8. Isolate critical services and implement failover mechanisms to maintain availability during potential DoS attempts.