Summary
Sencho's login endpoint improperly trusted client-supplied X-Forwarded-For values when applying login-rate limits. A remote attacker may rotate this apparent address to bypass those limits, increasing the feasibility of authentication attacks when the endpoint is exposed and proxy trust is not explicitly configured.
Sencho's login endpoint improperly trusted client-supplied X-Forwarded-For values when applying login-rate limits. A remote attacker may rotate this apparent address to bypass those limits, increasing the feasibility of authentication attacks when the endpoint is exposed and proxy trust is not explicitly configured.
Affected context
The issue occurs in Sencho deployments up to version 0.94.1 where the /api/auth/login endpoint uses X-Forwarded-For data to identify clients for login limiting without a clearly defined trusted-proxy boundary. Risk is higher when the endpoint is remotely reachable and forwarding headers can be supplied or altered by an untrusted client.
The issue occurs in Sencho deployments up to version 0.94.1 where the /api/auth/login endpoint uses X-Forwarded-For data to identify clients for login limiting without a clearly defined trusted-proxy boundary. Risk is higher when the endpoint is remotely reachable and forwarding headers can be supplied or altered by an untrusted client.
Exploit preconditions
- Attack surface: The remotely accessible /api/auth/login endpoint. - Required access: No authenticated account is necessarily required; network
access to the login endpoint may be sufficient.
- Trigger point: Login-rate-limit evaluation based on the apparent client
address.
- Why exploitation is possible: The application accepts client-controlled
forwarding information without restricting its use to requests received
through explicitly trusted proxies, allowing the limiter's client identity
to be varied.
- Attack surface: The remotely accessible /api/auth/login endpoint. - Required access: No authenticated account is necessarily required; network
access to the login endpoint may be sufficient.
- Trigger point: Login-rate-limit evaluation based on the apparent client
address.
- Why exploitation is possible: The application accepts client-controlled
forwarding information without restricting its use to requests received
through explicitly trusted proxies, allowing the limiter's client identity
to be varied.
Why this happens
The underlying bug is an improper authentication-control design mapped to CWE-287. The login limiter treated X-Forwarded-For as authoritative without establishing which proxy networks were trusted. Because that header can be client-controlled outside a trusted proxy boundary, the application could associate repeated login attempts with different apparent client addresses rather than consistently enforcing protections for the actual source or account identity.
The underlying bug is an improper authentication-control design mapped to CWE-287. The login limiter treated X-Forwarded-For as authoritative without establishing which proxy networks were trusted. Because that header can be client-controlled outside a trusted proxy boundary, the application could associate repeated login attempts with different apparent client addresses rather than consistently enforcing protections for the actual source or account identity.
Potential impact
- An attacker may bypass or weaken IP-based login throttling.
- The vulnerability could increase the feasibility of password-guessing or credential-stuffing activity.
- Account-protection controls may be less effective against automated authentication attempts.
- Increased authentication traffic could contribute to service degradation.
- An attacker may bypass or weaken IP-based login throttling.
- The vulnerability could increase the feasibility of password-guessing or credential-stuffing activity.
- Account-protection controls may be less effective against automated authentication attempts.
- Increased authentication traffic could contribute to service degradation.
General mitigation guidance
Mitigation generally focuses on treating forwarding headers as untrusted by default and defining explicit proxy trust boundaries. Secure-by-default designs can ignore client-provided forwarding headers unless requests arrive from configured proxy CIDRs, normalize the resulting client identity, and apply independent failed-attempt limits keyed to account identity. Rate limits should be enforced at multiple appropriate layers, and authentication services should run with minimal privileges. Input trust should be reduced by deriving source metadata from trusted transport infrastructure rather than arbitrary request headers.
Mitigation generally focuses on treating forwarding headers as untrusted by default and defining explicit proxy trust boundaries. Secure-by-default designs can ignore client-provided forwarding headers unless requests arrive from configured proxy CIDRs, normalize the resulting client identity, and apply independent failed-attempt limits keyed to account identity. Rate limits should be enforced at multiple appropriate layers, and authentication services should run with minimal privileges. Input trust should be reduced by deriving source metadata from trusted transport infrastructure rather than arbitrary request headers.
How teams detect issues like this
Detection may include static-analysis and code-review searches for authentication or rate-limiting logic that directly trusts X-Forwarded-For or similar headers without proxy allowlists. Review signals include IP-only throttling, missing account-keyed failure limits, and inconsistent normalization of client identity. Runtime monitoring can look for rapidly changing forwarding headers, repeated failures across many apparent addresses, and unusual login bursts. Policy enforcement can require documented trusted-proxy configuration and security tests for header spoofing scenarios; automated review tools may help identify these patterns.
Detection may include static-analysis and code-review searches for authentication or rate-limiting logic that directly trusts X-Forwarded-For or similar headers without proxy allowlists. Review signals include IP-only throttling, missing account-keyed failure limits, and inconsistent normalization of client identity. Runtime monitoring can look for rapidly changing forwarding headers, repeated failures across many apparent addresses, and unusual login bursts. Policy enforcement can require documented trusted-proxy configuration and security tests for header spoofing scenarios; automated review tools may help identify these patterns.
Sources
| Source | Link |
|---|---|
| gist. | gist.github.com/ |
| github. | github.com/ |
| github. | github.com/ |
| github. | github.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
