CVE-2026-55375
MEDIUMCVE-2026-55375 is a medium-severity (CVSS 5.3) vulnerability in jleehr/canto-saas-api. O3 Security confirms whether CVE-2026-55375 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
canto-saas-api: OAuth credentials exposed in URL query string and exception messages
Real-World Exposure
jleehr/canto-saas-apiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
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 returnsnull; the parameters are available viagetFormParams(). - Exception messages are sanitized before being rethrown: the values of
app_secret,refresh_tokenandcodeare masked (including url-encoded, differently cased and JSON-embedded variants).
Workarounds
If you cannot upgrade:
- Treat web server, proxy and APM logs of systems performing Canto OAuth requests as secret material and restrict access to them.
- Catch
AuthorizationFailedExceptionin your application and strip the query string from the message before logging or forwarding it.
If your logs may have been exposed, rotate the affected Canto app secret.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | jleehr/canto-saas-api | all versions | 3.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jleehr/canto-saas-api. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update jleehr/canto-saas-api to 3.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55375 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-55375 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-55375. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55375 in your dependencies?
O3 detects CVE-2026-55375 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.