CVE-2024-9355 Overview
A vulnerability was discovered in Golang FIPS OpenSSL that allows a malicious user to exploit uninitialized memory handling in FIPS mode. This flaw enables an attacker to randomly cause an uninitialized buffer length variable with a zeroed buffer to be returned. Additionally, it may be possible to force a false positive match between non-equal hashes when comparing a trusted computed HMAC sum to an untrusted input sum if an attacker can send a zeroed buffer in place of a pre-computed sum. The vulnerability also allows forcing a derived key to be all zeros instead of an unpredictable value, with potential follow-on implications for the Go TLS stack.
Critical Impact
This uninitialized memory vulnerability in FIPS mode can lead to cryptographic bypass scenarios, allowing false positive hash comparisons and predictable derived keys, potentially compromising TLS security.
Affected Products
- Golang FIPS OpenSSL (FIPS mode implementations)
- Red Hat products using golang-fips/openssl
- Go applications utilizing the affected FIPS OpenSSL bindings
Discovery Timeline
- 2024-10-01 - CVE-2024-9355 published to NVD
- 2025-10-02 - Last updated in NVD database
Technical Details for CVE-2024-9355
Vulnerability Analysis
This vulnerability falls under CWE-457 (Use of Uninitialized Variable), a class of memory safety issues that occur when code reads from memory locations before they have been properly initialized. In the context of Golang FIPS OpenSSL, this manifests specifically when operating in FIPS mode, where cryptographic operations must adhere to strict security standards.
The flaw creates multiple attack surfaces. First, an uninitialized buffer length variable can be returned with a zeroed buffer, which may cause cryptographic operations to process incorrect data lengths. Second, hash comparison operations become vulnerable to false positives—an attacker who controls input can provide a zeroed buffer that may incorrectly match against legitimately computed HMAC sums. Third, key derivation functions may produce all-zero keys instead of cryptographically secure random values.
The local attack vector requires the attacker to have some level of access to the system, but the high complexity factor indicates that successful exploitation requires specific conditions to be met. The implications for the Go TLS stack are particularly concerning, as compromised key derivation or hash validation could undermine the security of encrypted communications.
Root Cause
The root cause lies in improper initialization of buffer length variables within the Golang FIPS OpenSSL codebase when operating in FIPS mode. The code path fails to ensure that buffer length variables are properly initialized before use, leading to scenarios where zeroed or undefined values are processed. This initialization failure occurs in critical cryptographic code paths including HMAC computation and key derivation functions.
Attack Vector
The attack requires local access to the target system. An attacker with local privileges can exploit this vulnerability by manipulating inputs to cryptographic functions in FIPS mode. The attack methodology involves sending specially crafted zeroed buffers in place of expected cryptographic values, potentially bypassing hash verification or causing predictable key generation. The vulnerability is particularly dangerous in scenarios where untrusted input is compared against computed cryptographic sums, as the uninitialized memory behavior can cause false positive matches.
Detection Methods for CVE-2024-9355
Indicators of Compromise
- Unexpected zeroed values in HMAC comparison operations within Go applications running in FIPS mode
- Derived cryptographic keys consisting entirely of zero bytes in affected applications
- TLS handshake anomalies or authentication bypasses in Go-based services using FIPS OpenSSL
- Log entries indicating hash verification passed when it should have failed
Detection Strategies
- Monitor Go applications using FIPS mode for abnormal cryptographic operation results
- Implement integrity checking for key derivation outputs to detect all-zero key generation
- Review application logs for hash comparison operations that may indicate false positive matches
- Use memory debugging tools to identify uninitialized variable access in affected code paths
Monitoring Recommendations
- Enable enhanced logging for cryptographic operations in FIPS-enabled Go applications
- Implement runtime monitoring to detect unusual patterns in hash verification outcomes
- Configure alerts for TLS stack anomalies in services using golang-fips/openssl
- Regularly audit HMAC and key derivation function outputs for unexpected zero values
How to Mitigate CVE-2024-9355
Immediate Actions Required
- Apply the latest security patches from Red Hat for affected products (see advisory links below)
- Update golang-fips/openssl to the patched version as referenced in GitHub Pull Request #198
- Review and rebuild Go applications that depend on the affected FIPS OpenSSL bindings
- Temporarily disable FIPS mode if patches cannot be immediately applied and security requirements permit
Patch Information
Red Hat has released multiple security advisories addressing this vulnerability across various products. Organizations should consult the relevant advisories for their specific deployments:
- RHSA-2024:7502
- RHSA-2024:7550
- RHSA-2024:8327
- RHSA-2024:8678
- RHSA-2024:8847
- RHSA-2024:9551
- RHSA-2024:10133
- RHSA-2025:2416
- RHSA-2025:7118
- RHSA-2025:7256
- RHSA-2025:7624
The fix addresses the uninitialized memory issue by ensuring proper initialization of buffer length variables before use in FIPS mode cryptographic operations. Additional details are available in Red Hat Bug Report #2315719.
Workarounds
- Implement application-level validation to reject all-zero cryptographic values in hash comparisons and key derivations
- Add secondary verification checks for critical HMAC operations before trusting comparison results
- Consider temporarily running affected applications in non-FIPS mode if compliance requirements allow and patches are not yet available
- Restrict local access to systems running vulnerable FIPS-enabled Go applications to reduce attack surface
# Configuration example
# Verify golang-fips/openssl version and update if necessary
go list -m github.com/golang-fips/openssl
go get github.com/golang-fips/openssl@latest
# For Red Hat systems, apply security updates
sudo dnf update --security
# Verify patch application
rpm -qa | grep golang
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
