CVE-2025-58187: Golang Go DOS Vulnerability

CVE-2025-58187 Overview

CVE-2025-58187 is an Algorithmic Complexity Attack vulnerability affecting Golang Go's certificate validation implementation. Due to the design of the name constraint checking algorithm, the processing time of some inputs scales non-linearly with respect to the size of the certificate. This affects programs which validate arbitrary certificate chains, potentially enabling denial-of-service attacks against services that process untrusted certificates.

Critical Impact

Attackers can craft malicious certificates that cause excessive CPU consumption during validation, leading to denial of service in applications that process untrusted certificate chains.

Affected Products

• Golang Go (multiple versions)

Discovery Timeline

• 2025-10-29 - CVE CVE-2025-58187 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2025-58187

Vulnerability Analysis

This vulnerability (CWE-407: Inefficient Algorithmic Complexity) exists within the name constraint checking functionality of Go's X.509 certificate validation implementation. When processing certificates with specially crafted name constraints, the algorithm exhibits non-linear time complexity, meaning the processing time grows disproportionately as the input size increases. This algorithmic inefficiency can be weaponized by attackers to exhaust system resources.

The vulnerability is network-accessible and requires no authentication or user interaction to exploit. An attacker can submit malicious certificates to any service that validates certificate chains, causing the service to consume excessive CPU cycles during the validation process. The impact is limited to availability—there is no compromise of confidentiality or integrity.

Root Cause

The root cause lies in the design of the name constraint checking algorithm in Go's crypto/x509 package. Name constraints in X.509 certificates define permitted or excluded namespaces for subordinate certificates. The existing implementation processes these constraints using an algorithm with poor time complexity characteristics when handling certain input patterns. This allows adversarial inputs to trigger worst-case performance scenarios, resulting in resource exhaustion.

Attack Vector

The attack vector is network-based and can be exploited by any unauthenticated remote attacker. The attack targets applications that validate certificate chains from untrusted sources, which includes:

• TLS servers accepting client certificates
• Certificate transparency log processors
• Certificate validation services and APIs
• Any Go application using crypto/x509.Verify() with untrusted input

An attacker constructs a certificate chain containing name constraints designed to maximize processing time. When the target application attempts to validate this certificate chain, the inefficient algorithm causes the validation to consume excessive CPU time, degrading service performance or causing complete denial of service.

The vulnerability can be exploited by submitting a malicious certificate during TLS handshake, certificate upload, or any other certificate processing workflow. For detailed technical information, see the Go.dev Issue Tracker Update and the Golang Announce Discussion.

Detection Methods for CVE-2025-58187

Indicators of Compromise

• Abnormally high CPU utilization in Go applications during certificate validation operations
• Unusually long response times for TLS handshakes or certificate processing endpoints
• Certificate chains containing excessive or deeply nested name constraints
• Repeated certificate validation requests from single sources with unusual certificate structures

Detection Strategies

• Monitor CPU consumption patterns for Go processes handling certificate validation
• Implement rate limiting on endpoints accepting certificate submissions
• Add timeouts to certificate validation operations to detect long-running validations
• Log and alert on certificate chains with unusually large name constraint extensions

Monitoring Recommendations

• Enable detailed logging for certificate validation failures and timeouts
• Set up alerting for Go application CPU usage exceeding baseline thresholds
• Monitor TLS handshake duration metrics for anomalies
• Track certificate validation request rates per source IP

How to Mitigate CVE-2025-58187

Immediate Actions Required

• Update Golang Go to the latest patched version immediately
• Implement timeouts for certificate validation operations as a defense-in-depth measure
• Review applications that process certificates from untrusted sources
• Consider rate limiting certificate validation endpoints until patches are applied

Patch Information

Golang has released patches to address this vulnerability. The fix modifies the name constraint checking algorithm to ensure linear time complexity for all inputs. Administrators should apply the update available through the Go.dev Change Log Entry. Additional vulnerability details are documented in the Go.dev Vulnerability Report GO-2025-4007.

Workarounds

• Implement strict timeouts on certificate validation to limit potential resource exhaustion
• Add rate limiting for certificate submission endpoints
• Filter or reject certificates with unusually large name constraint extensions
• Consider using certificate validation in isolated worker processes with resource limits

# Example: Setting resource limits for Go applications on Linux
# Limit CPU time to prevent unbounded resource consumption

# Using systemd service configuration
[Service]
CPUQuota=50%
TimeoutSec=30

# Or using ulimit before starting the application
ulimit -t 60  # Limit CPU time to 60 seconds