CVE-2026-48031: go-base Auth Bypass Vulnerability

CVE-2026-48031 Overview

CVE-2026-48031 is a hardcoded credentials vulnerability [CWE-798] in go-base, a Go RESTful API boilerplate template that provides JSON Web Token (JWT) authentication backed by PostgreSQL. Versions prior to 2026-05-18 ship with the JWT signing secret hardcoded to the string "random". Any attacker who reads the public repository can forge tokens for arbitrary users, including administrative roles, and bypass authentication on all protected endpoints. The hardcoded value is set in the dev.env template and again as a programmatic fallback in cmd/serve.go, so the application uses it even when no .env file is present.

Critical Impact
Attackers can forge JWTs for any user, including admins, and fully bypass authentication on every protected endpoint.

Affected Products

go-base versions prior to 2026-05-18
Applications derived from the go-base boilerplate that reuse its default JWT configuration
Deployments relying on the dev.env template or the Viper default in cmd/serve.go

Discovery Timeline

2026-08-03 - CVE-2026-48031 published to the National Vulnerability Database (NVD)
2026-08-03 - Last updated in NVD database

Technical Details for CVE-2026-48031

Vulnerability Analysis

The vulnerability stems from a hardcoded JWT signing secret in the go-base template. The secret literal "random" is defined in two locations: line 10 of the dev.env template and line 35 of cmd/serve.go, which registers it as a Viper default. This means the application signs and verifies JWTs with a publicly known value even when operators forget to supply an .env file. Because the secret is embedded in a public repository, an attacker does not need any network reconnaissance to obtain it.

An earlier mitigation attempt in auth/jwt/tokenauth.go (lines 22 through 25) only detected the exact literal "random" and replaced it with an in-memory key. That key was never persisted, so every process restart invalidated all previously issued tokens, converting the weak-secret condition into a denial-of-service condition. The check also failed to catch other weak or default secrets, leaving the forgery path open in most misconfigurations.

Root Cause

The root cause is the use of hardcoded credentials [CWE-798] as both a configuration template value and a programmatic fallback. Cryptographic signing keys must be generated per deployment and loaded from a trusted secret store. Embedding them in source code or default configuration files exposes the entire authentication boundary of the application.

Attack Vector

Exploitation is fully remote and requires no privileges or user interaction. An attacker reads the public go-base source, obtains the secret "random", and uses it to sign a JWT with arbitrary claims, including elevated role fields. The forged token is then submitted to any protected endpoint, and the server validates it as legitimate.

// Patch reference from auth/jwt/errors.go and cmd/serve.go
// The upstream fix removes the hardcoded "random" default and
// requires operators to supply a strong JWT signing secret via
// environment configuration rather than a Viper default.
// Source: https://github.com/dhax/go-base/commit/cc82b9740fa6b08e0fad409cd4b418e240dd0e00

See the GitHub Security Advisory GHSA-mqq6-462x-jxmm and Pull Request #31 for the full remediation.

Detection Methods for CVE-2026-48031

Indicators of Compromise

JWTs presented to the API that verify successfully against the literal secret "random" (HS256 signature).
Authentication events for privileged accounts originating from IP addresses or user agents not previously associated with those users.
Successful access to admin-only endpoints without a corresponding prior login event in application logs.

Detection Strategies

Statically scan repositories and container images for the string "random" in dev.env, cmd/serve.go, or Viper SetDefault("jwt_secret", ...) calls.
Attempt to verify a sample of production JWTs offline against the known weak secret; any successful verification confirms exposure.
Correlate JWT iat and exp claims against server-side session records to identify tokens the server never issued.

Monitoring Recommendations

Alert on authentication decisions for high-privilege roles that lack a matching login or token-issuance event.
Log the JWT kid and signing algorithm on every request and flag tokens signed with unexpected keys or alg values.
Monitor for spikes in 401/403 responses followed by successful authenticated requests from the same source, which can indicate secret-guessing.

How to Mitigate CVE-2026-48031

Immediate Actions Required

Upgrade go-base to version 2026-05-18 or later, which removes the hardcoded default from both dev.env and cmd/serve.go.
Rotate the JWT signing secret to a cryptographically random value of at least 256 bits and invalidate all previously issued tokens.
Audit application logs for authentication events issued during the exposure window and revoke sessions for any account that cannot be confirmed as legitimate.

Patch Information

The upstream fix is delivered in commit cc82b97 via Pull Request #31. The patch removes the "random" fallback, eliminates the in-memory replacement key that caused restart-time token invalidation, and requires the operator to supply a JWT secret through configuration. Full details are documented in GHSA-mqq6-462x-jxmm.

Workarounds

Override the JWT secret at startup by exporting a strong JWT_SECRET environment variable and confirming the application reads it before serving traffic.
Remove or edit the dev.env template so it no longer contains the literal "random" value, and add a startup check that refuses to boot on weak or default secrets.
Terminate the application behind a reverse proxy that enforces mutual TLS or an additional authentication layer until the upgrade is applied.

bash

# Generate a strong JWT secret and export it before starting go-base
export JWT_SECRET="$(openssl rand -base64 48)"

# Verify no hardcoded value remains in the deployed configuration
grep -R "random" ./dev.env ./cmd/serve.go && echo "WEAK SECRET PRESENT" || echo "OK"

# Start the server only if the secret is set and non-default
[ -n "$JWT_SECRET" ] && [ "$JWT_SECRET" != "random" ] && ./go-base serve