CVE-2025-58188: Golang Go DOS Vulnerability

CVE-2025-58188 Overview

CVE-2025-58188 is a Denial of Service vulnerability affecting Golang's certificate chain validation functionality. When validating certificate chains that contain DSA (Digital Signature Algorithm) public keys, programs can panic due to an interface cast that incorrectly assumes all public key types implement the Equal method. This vulnerability impacts any Go application that validates arbitrary certificate chains, potentially allowing attackers to crash services by presenting specially crafted certificates containing DSA public keys.

Critical Impact

Applications performing certificate validation against untrusted or user-supplied certificate chains can be crashed remotely, causing service disruption and potential availability issues for critical infrastructure.

Affected Products

• Golang Go (multiple versions)
• Applications built with Go that perform certificate chain validation
• Services accepting TLS connections with client certificate validation

Discovery Timeline

• 2025-10-29 - CVE CVE-2025-58188 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2025-58188

Vulnerability Analysis

This vulnerability stems from a type assertion issue in Go's certificate validation code. The certificate chain verification logic performs an interface cast on public key objects, assuming they implement the Equal method. However, DSA public keys do not implement this method, causing a runtime panic when the type assertion fails.

The vulnerability is classified under CWE-295 (Improper Certificate Validation), as the certificate validation process fails to properly handle all valid certificate types. This creates a denial of service condition when processing certificates containing DSA public keys during chain validation.

The attack can be executed remotely over the network without requiring authentication or user interaction. An attacker simply needs to present a certificate chain containing a DSA public key to trigger the panic condition in vulnerable applications.

Root Cause

The root cause is an incomplete interface implementation assumption in Go's cryptographic certificate handling code. The code assumes all public key types support comparison via the Equal method, but DSA public keys lack this implementation. When the certificate validation code attempts to cast the public key to an interface with the Equal method, the operation panics for DSA keys.

This represents a type confusion issue where the code fails to account for the differences between RSA, ECDSA, and DSA key type implementations. While RSA and ECDSA keys properly implement the comparison interface, DSA keys were not updated to include this functionality.

Attack Vector

The attack vector leverages the certificate chain validation process in Go applications. An attacker can exploit this vulnerability by:

1. Creating or obtaining a certificate chain that includes a certificate with a DSA public key
2. Presenting this certificate chain to a vulnerable Go application during TLS handshake or explicit certificate validation
3. The application's certificate verification code triggers the interface cast, causing an unhandled panic
4. The application crashes, resulting in denial of service

This attack requires no authentication and can be executed against any network-accessible service that validates certificates. The vulnerability is particularly concerning for TLS servers implementing client certificate authentication or any service that processes user-submitted certificates.

The vulnerability mechanism involves the interface type assertion in Go's certificate handling. When the validation code encounters a DSA public key during chain verification, it attempts to invoke comparison methods that DSA key types do not implement, resulting in a runtime panic. For complete technical details, see the Go.dev Issue Tracker Report.

Detection Methods for CVE-2025-58188

Indicators of Compromise

• Application crashes with panic messages referencing certificate validation or public key comparison operations
• Stack traces containing references to crypto/x509 package functions
• Unexpected service restarts correlating with TLS connection attempts
• Log entries indicating panic recovery in certificate handling code paths

Detection Strategies

• Monitor application logs for panic events related to certificate validation or crypto/x509 operations
• Implement crash dump analysis to identify panics originating from certificate chain verification
• Review TLS handshake failures for patterns indicating DSA certificate presentation
• Deploy application performance monitoring to detect sudden service terminations

Monitoring Recommendations

• Enable detailed logging for certificate validation operations in production environments
• Configure alerting for application crashes and unexpected restarts
• Implement circuit breakers for certificate validation operations to contain potential DoS impact
• Monitor for unusual certificate types being presented during TLS negotiations

How to Mitigate CVE-2025-58188

Immediate Actions Required

• Update Golang to the latest patched version that addresses this vulnerability
• Review applications for certificate chain validation against untrusted sources
• Implement panic recovery handlers around certificate validation code as a temporary measure
• Consider restricting accepted certificate types to exclude DSA if not operationally required

Patch Information

Golang has released patches to address this vulnerability. The fix ensures proper handling of DSA public keys during certificate chain validation by implementing the necessary comparison methods or adding appropriate type checks.

For detailed patch information, refer to the Go.dev Change Log Entry. Additional vulnerability details are available in the Go.dev Vulnerability Report.

The Golang Announcement Group Post provides official guidance on updating affected installations.

Workarounds

• Implement panic recovery wrappers around certificate validation code to prevent application crashes
• Add pre-validation checks to reject certificates with DSA public keys if not required for business operations
• Deploy reverse proxies or load balancers that perform certificate validation before requests reach vulnerable applications
• Consider using certificate pinning to restrict accepted certificates to known, safe configurations

Until patching is complete, applications can implement defensive panic recovery to maintain availability:

# Check current Go version
go version

# Update to latest patched Go version
# Download from https://go.dev/dl/

# Rebuild applications with patched Go version
go build -o application_name .