canto-saas-api: Authenticated API requests can be redirected via unencoded path variables
Summary
In affected versions, Request::buildRequestUrl() inserts path variables into
the request URL without URL encoding (implode('/', $pathVariables)). All
request classes implementing getPathVariables() are affected, e.g.
GetContentDetailsRequest (scheme, contentId).
If a consuming application passes untrusted input (such as an ID taken from
an HTTP request parameter) as a path variable, characters like ../, ? or
# are sent verbatim and can change the path of the resulting API request.
## Impact
An attacker who controls a path variable value can redirect the
library's authenticated request — the Bearer access token is attached in
AbstractEndpoint::sendRequest() — to a different API endpoint of the same
Canto instance, causing unintended reads or writes with the privileges of the
configured app. The impact depends on how the consuming application sources
path variable values; applications that only pass trusted, validated IDs are
not exploitable.
## Patches
Fixed in 3.0.0: every path segment is encoded with rawurlencode() before
being inserted into the request URL.
## Workarounds
If you cannot upgrade, validate untrusted values before passing them to
request classes, e.g. enforce an allowlist pattern such as
^[A-Za-z0-9_-]+$ for content IDs and schemes.