CVE-2025-59464 Overview
A memory leak vulnerability exists in Node.js's OpenSSL integration that occurs when converting X.509 certificate fields to UTF-8 without properly freeing the allocated buffer. When applications call socket.getPeerCertificate(true), each certificate field leaks memory, allowing remote clients to trigger steady memory growth through repeated TLS connections. Over time this can lead to resource exhaustion and denial of service.
Critical Impact
Remote attackers can cause denial of service through memory exhaustion by initiating repeated TLS connections that trigger the memory leak in certificate processing.
Affected Products
- Node.js (versions with vulnerable OpenSSL integration)
Discovery Timeline
- 2026-01-20 - CVE CVE-2025-59464 published to NVD
- 2026-01-21 - Last updated in NVD database
Technical Details for CVE-2025-59464
Vulnerability Analysis
This vulnerability falls under CWE-400 (Uncontrolled Resource Consumption) and represents a memory leak condition in Node.js's handling of TLS certificate data. The flaw exists in the code path that processes X.509 certificate fields, specifically when converting certificate field values to UTF-8 encoding for JavaScript consumption.
When an application retrieves peer certificate information using socket.getPeerCertificate(true), the underlying OpenSSL integration allocates memory buffers to hold the UTF-8 converted certificate field data. The vulnerability arises because these buffers are not properly deallocated after use, causing a persistent memory leak with each certificate field processed.
Root Cause
The root cause is improper memory management in the OpenSSL binding layer. When X.509 certificate fields are converted to UTF-8 strings for exposure to the JavaScript runtime, the allocated memory buffers are not freed after the data is copied. This creates a classic memory leak pattern where each invocation of getPeerCertificate(true) incrementally consumes additional heap memory without release.
Attack Vector
The vulnerability is exploitable over the network without authentication. An attacker can establish repeated TLS connections to a vulnerable Node.js server that calls socket.getPeerCertificate(true) on incoming connections. Each connection causes the server to leak memory associated with processing the client's certificate fields.
The attack requires user interaction (UI:R) in the sense that the server application must be configured to retrieve peer certificates. In practice, this is common in mutual TLS (mTLS) deployments where servers validate client certificates. Over an extended period, the cumulative memory leaks can exhaust available system memory, resulting in denial of service through resource exhaustion.
Detection Methods for CVE-2025-59464
Indicators of Compromise
- Gradual increase in Node.js process memory consumption over time without corresponding workload increase
- Memory growth correlated with TLS connection volume, particularly in mTLS configurations
- Out-of-memory errors or process crashes in long-running Node.js TLS servers
- System-level memory exhaustion warnings on servers handling certificate validation
Detection Strategies
- Monitor Node.js process resident set size (RSS) and heap usage metrics for abnormal growth patterns
- Implement alerting on memory consumption thresholds for Node.js services performing TLS certificate operations
- Audit application code for usage of socket.getPeerCertificate(true) in TLS connection handlers
- Review connection logs for unusual patterns of repeated TLS handshakes from single sources
Monitoring Recommendations
- Deploy application performance monitoring (APM) tools to track memory allocation trends in Node.js services
- Configure process-level memory limits and monitoring for Node.js applications handling TLS traffic
- Implement automated restarts or circuit breakers for services exhibiting memory growth anomalies
- Enable verbose TLS logging to correlate memory growth with certificate processing activity
How to Mitigate CVE-2025-59464
Immediate Actions Required
- Review Node.js applications for usage of socket.getPeerCertificate(true) and assess exposure
- Apply the latest Node.js security updates as documented in the December 2025 security releases
- Implement connection rate limiting for TLS endpoints to reduce potential memory leak impact
- Configure memory limits and automatic restarts for affected Node.js processes as a temporary measure
Patch Information
The Node.js security team has addressed this vulnerability in their December 2025 security releases. Administrators should upgrade to patched versions as soon as possible. For detailed patch information and affected version ranges, refer to the Node.js December 2025 Security Blog.
Workarounds
- Avoid calling socket.getPeerCertificate(true) unless strictly necessary for application functionality
- Implement periodic process restarts for long-running services as a temporary mitigation
- Deploy connection rate limiting at the network or application layer to reduce the rate of potential memory leaks
- Consider caching certificate validation results to minimize repeated calls to the vulnerable function
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
