Description

regclient is a Docker and OCI Registry Client in Go. Prior to version 0.11.5, credentials for a registry may be inadvertently leaked to external servers. A prerequisite for this attack is a malicious registry server, a malicious blob store, or a registry that does not restrict the external URLs for foreign blobs. Version 0.11.5 fixes the issue.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.8",
  "pubDate": "2026-08-12T15:17:37.507Z",
  "pubdate": "2026-08-12T15:17:37.507Z",
  "executiveSummary": "An information disclosure vulnerability exists in regclient prior to version 0.11.5, where sensitive registry credentials can be inadvertently leaked to unauthorized external servers.\nThe vulnerability impacts the regclient Docker and OCI registry client in Go, posing significant risk implications regarding credential compromise and unauthorized access to private container registries.\nThe attacker capabilities rely on positioning a malicious registry server, a malicious blob store, or leveraging a registry configuration that fails to restrict external URLs for foreign blobs.\nExploitation requirements necessitate that a user interacts with a compromised or malicious registry ecosystem capable of prompting the client to issue requests containing authorization materials to arbitrary external endpoints.\nThe primary impact is the unauthorized exfiltration of authentication tokens or credentials, which could lead to lateral movement, supply chain compromise, or further unauthorized data access within containerized environments.",
  "technicalDetails": "The vulnerability resides in how regclient handles requests and redirects, specifically regarding the handling of foreign blobs or interactions with untrusted registry endpoints prior to version 0.11.5.\nThe root cause stems from the client's failure to adequately validate or restrict destination URLs when processing layer references or foreign blob redirects, causing authorization headers or stored credentials to be transmitted across security boundaries.\nThe attack flow initiates when a client interacts with a malicious registry server or an unverified blob store. During the pull or push operation, the malicious server responds with a reference pointing to an external server or an arbitrary URL under the attacker's control, often disguised as a foreign blob redirection.\nUpon receiving the directive, the vulnerable regclient component automatically includes sensitive authentication material—such as registry credentials or authorization tokens—in the outbound HTTP request headers destined for the external, untrusted server.\nNetwork exposure is defined by the operational scope of the client interacting with external registries over standard protocols (HTTP/HTTPS). Authentication requirements and privilege requirements for the victim user depend on the standard interaction model with the targeted registry, but successful exploitation yields immediate credential harvesting on the attacker-controlled endpoint.\nThe payload behavior involves capturing the leaked credentials from the HTTP request headers at the malicious receiver, granting the attacker persistent or session-based access to the legitimate registries associated with those credentials for post-exploitation activities."
}