EUVD-2026-368893

fkie_cve-2026-55375

canto-saas-api is a PHP library for interacting with the Canto SaaS API. Prior to version 3.0.0, OAuth2Request::getQueryParams() places app_id, app_secret, refresh_token, and code in the URL query string of token POST requests, allowing access logs, proxy logs, and APM traces to persist the credentials in plaintext. When a token request fails, OAuth2::obtainAccessToken() also passes the credential-bearing Guzzle request URI into AuthorizationFailedException, so application logs and error trackers can record the same secrets. An attacker with access to affected telemetry can obtain Canto credentials and use them to request access tokens for the tenant. This issue is fixed in version 3.0.0.

GHSA-37pm-83g7-r22v — canto-saas-api: OAuth credentials exposed in URL query string and exception messages

Affected: Packagist: jleehr/canto-saas-api

## Summary

In affected versions, the OAuth2 token request sends `app_id`, `app_secret`, `refresh_token` and `code` as URL query parameters of the POST request to `https://oauth.<domain>/oauth/api/oauth2/token`. Request URLs are commonly recorded in access logs, proxy logs and APM traces, so the application secret and refresh token can be persisted in plain text outside the application's control.

In addition, when the token request fails, the Guzzle exception message — which contains the full request URI including the credentials — was passed unmodified into the `AuthorizationFailedException` thrown by `OAuth2::obtainAccessToken()`. Applications that log exceptions or forward them to error trackers (e.g. Sentry) may therefore have recorded the app secret in their logs.

## Impact

An attacker with access to web server logs, proxy logs, APM tracing data or application error logs of a consumer of this library can obtain the Canto `app_secret`, `refresh_token` or authorization `code` and use them to obtain access tokens for the Canto tenant.

## Patches

Fixed in 3.0.0:

- OAuth credentials are sent in the form-encoded POST body instead of the URL query string (RFC 6749 §2.3.1). `OAuth2Request::getQueryParams()` now returns `null`; the parameters are available via `getFormParams()`. - Exception messages are sanitized before being rethrown: the values of `app_secret`, `refresh_token` and `code` are masked (including url-enco…

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EUVD-2026-368893

fkie_cve-2026-55375

GHSA-37pm-83g7-r22v — canto-saas-api: OAuth credentials exposed in URL query string and exception messages