CVE-2024-9355 is a vulnerability identified in the Golang FIPS OpenSSL implementation, where an uninitialized variable related to buffer length can lead to security weaknesses when operating in FIPS mode. Specifically, the flaw allows a malicious actor to cause the system to return a zeroed buffer length variable that was never properly initialized. This can result in multiple cryptographic failures: first, it may enable an attacker to force a false positive match between a trusted computed HMAC sum and an untrusted input sum by substituting a zeroed buffer for the pre-computed sum. Second, it can cause a derived cryptographic key to be all zeros instead of a securely generated unpredictable value. These failures compromise the integrity and confidentiality of cryptographic operations, potentially undermining the security of TLS connections managed by the Go TLS stack. The vulnerability requires local access with low privileges and has a high attack complexity, meaning exploitation is non-trivial and cannot be performed remotely or without some level of system access. No user interaction is required for exploitation. The vulnerability has a CVSS 3.1 base score of 6.5, categorized as medium severity, reflecting the significant but not critical impact on confidentiality and integrity, with limited availability impact. No known exploits have been reported in the wild yet, but the implications for cryptographic trustworthiness are serious, especially in environments relying on FIPS-validated cryptography for compliance and security assurance. The absence of patch links suggests that fixes may still be pending or in development.

For European organizations, this vulnerability poses a risk primarily to the confidentiality and integrity of sensitive data protected by cryptographic operations using Go's FIPS OpenSSL implementation. Organizations in sectors such as finance, healthcare, telecommunications, and critical infrastructure that rely on Go for secure communications and data protection could face risks of data tampering, unauthorized data disclosure, or session hijacking if the vulnerability is exploited. The possibility of false positive HMAC matches could allow attackers to bypass authentication or integrity checks, while zeroed derived keys could weaken encryption strength, potentially exposing encrypted data. Given the complexity and requirement for local access, the threat is more pronounced in environments where insider threats or compromised local accounts exist. The impact on the Go TLS stack could affect secure web services, APIs, and internal communications, undermining trust in encrypted channels. Compliance with European data protection regulations such as GDPR could be jeopardized if cryptographic assurances are weakened, leading to potential legal and reputational consequences.

European organizations should proactively monitor updates from the Go project and related FIPS OpenSSL maintainers to apply patches as soon as they become available. In the interim, organizations should audit their use of Go cryptographic libraries to identify any reliance on the vulnerable FIPS OpenSSL components. Where feasible, consider temporarily disabling FIPS mode or using alternative cryptographic libraries that are not affected until a patch is applied. Implement additional cryptographic validation layers, such as independent HMAC verification, to detect anomalies caused by zeroed buffers or false positive matches. Restrict local access to systems running vulnerable Go components to trusted personnel only and enhance monitoring for suspicious activities indicative of exploitation attempts. Conduct thorough code reviews and penetration testing focused on cryptographic operations to identify potential exploitation vectors. Finally, update incident response plans to include scenarios involving cryptographic failures and potential insider threats exploiting this vulnerability.