Junglewise Threat Intelligence

CVE-2026-45793: Composer sensitive information disclosure in GitHub token validation

CVE-2026-45793 · Severity: high · CVSS 7.5 · Published 2026-07-15

Executive brief

Composer, a widely used dependency manager for the PHP programming language, contains a flaw that can lead to the accidental exposure of GitHub authentication tokens. When using certain GitHub Actions tokens that contain hyphens, the software fails to validate them correctly and may print the full, sensitive token into system logs or error consoles. If these logs are accessible to unauthorized individuals or stored in public continuous integration (CI) environments, it could allow attackers to hijack GitHub sessions and access private code repositories.

Technical details

A vulnerability in Composer's `BaseIO::loadConfiguration()` method arises from an overly restrictive regular expression (`^[.A-Za-z0-9_]+ Junglewise ) used to validate GitHub OAuth tokens. GitHub Actions `GITHUB_TOKEN` values using the `ghs_` format often contain hyphens, which fail this validation check. When validation fails, the rejected token is interpolated into an `UnexpectedValueException`, causing the plaintext sensitive token to be disclosed via stderr or CI logs. This exposure of sensitive information (CWE-200) allows anyone with access to build logs to obtain valid authentication credentials. The issue is resolved in versions 1.10.28, 2.2.28, and 2.9.8 by updating the validation logic and preventing token interpolation into exceptions.

Affected products

  • Composer Composer < 1.10.28, >= 2.0.0 < 2.2.28, >= 2.3.0 < 2.9.8

Timeline

  • 2026-05-13: patched: Fixes merged into branches 1.10, 2.2, and 2.9
  • 2026-07-15: disclosed: CVE-2026-45793 published

References

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