GitHub Actions / GitHub Actions

GitHub Composer CVE-2026-45793: GITHUB_TOKEN Leaks to CI Logs via Regex Miss

Fix GitHub Actions token leakage into CI logs caused by Composer's old regex rejecting new GITHUB_TOKEN format with hyphens Includes evidence for GitHub Actions troubleshooting demand.

Source-backed Last updated May 18, 2026 1 source Needs local verification

Category: GitHub Actions
Error signature: GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs
Quick fix: Verify the account session, API key, provider settings, and environment where the failing tool is running.
Updated: May 18, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for GitHub Actions, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs is a GitHub Actions failure pattern reported for developers trying to fix github actions token leakage into ci logs caused by composer's old regex rejecting new github_token format with hyphens. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Source: lilting.ch detailed analysis of CVE-2026-45793 disclosed May 13, 2026. Composer 2.3.0–2.9.7 rejected new GH Actions tokens containing hyphens (ghs_<id>_...), then embedded rejected token in exception messages written to stderr saved as job logs. Secret masking fails because ANSI color codes and line wrapping break contiguous string matching. Critical for paid Teams/Enterprise using setup-php or Composer in CI.

Common causes

Source: lilting.ch detailed analysis of CVE-2026-45793 disclosed May 13, 2026. Composer 2.3.0–2.9.7 rejected new GH Actions tokens containing hyphens (ghs_<id>_...), then embedded rejected token in exception messages written to stderr saved as job logs. Secret masking fails because ANSI color codes and line wrapping break contiguous string matching. Critical for paid Teams/Enterprise using setup-php or Composer in CI.

Quick fixes

Confirm the exact error signature matches GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs.
Check the GitHub Actions account, local tool state, and provider configuration involved in the failing workflow.
Verify the account session, API key, provider settings, and environment where the failing tool is running.

Platform/tool-specific checks

Verify the command, editor, extension, or API client that produced the error.
Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

Capture the exact error message and the command, editor action, or request that triggered it.
Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
Review the source evidence below and compare it with your environment.
Apply one change at a time and rerun the smallest failing action.
Keep the working fix documented for the team or deployment environment.

How to prevent it

Keep provider/tool configuration documented.
Record non-secret diagnostics such as tool version, provider name, model name, and command path.
Add a lightweight check before CI or production workflows depend on the tool.

Diagnostic flow for this page

Match GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs exactly before applying the quick fix.
Compare the failing environment with GitHub Actions versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs mean in GitHub Actions?

GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs indicates the workflow described by "GitHub Composer CVE-2026-45793: GITHUB_TOKEN Leaks to CI Logs via Regex Miss" failed in a GitHub Actions context. Start by confirming the exact signature and the component that emitted it.

What should I check first for GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs?

Check whether this cause matches your environment: Source: lilting.ch detailed analysis of CVE-2026-45793 disclosed May 13, 2026. Composer 2.3.0–2.9.7 rejected new GH Actions tokens containing hyphens (ghs_<id>_...), then embedded rejected token in exception messages written to stderr saved as job logs. Secret masking fails because ANSI color codes and line wrapping break contiguous string matching. Critical for paid Teams/Enterprise using setup-php or Composer in CI.

Is the GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs guidance source-backed?

The "GitHub Composer CVE-2026-45793: GITHUB_TOKEN Leaks to CI Logs via Regex Miss" page is labeled source-backed. It has 1 public source URL from lilting.ch, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs?

For "GitHub Composer CVE-2026-45793: GITHUB_TOKEN Leaks to CI Logs via Regex Miss", avoid applying "Verify the account session, API key, provider settings, and environment where the failing tool is running." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging GitHub OAuth token contains invalid characters — Composer rejects GITHUB_TOKEN due to hyphen regex miss, exposing plaintext tokens in job logs?

For "GitHub Composer CVE-2026-45793: GITHUB_TOKEN Leaks to CI Logs via Regex Miss", collect the failing GitHub Actions command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.