Description

Webhooks created by a collaborator keep firing after their repo access is revoked → ongoing real-time exfiltration of private repo content (incomplete revocation cleanup in `DeleteCollaboration`)

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.8",
  "pubDate": "2026-08-13T17:17:28.020Z",
  "pubdate": "2026-08-13T17:17:28.020Z",
  "executiveSummary": "An incomplete access revocation vulnerability exists within the repository collaboration management functionality where webhooks established by a collaborator continue to execute and fire even after the collaborator's repository access has been formally revoked.\nThe vulnerability leads to ongoing, real-time data exfiltration of private repository content by unauthorized external entities who no longer possess legitimate authorization or membership within the repository ecosystem.\nThe affected system involves repository collaboration and webhook management routines specifically tied to the DeleteCollaboration function.\nThe risk implications are severe, resulting in the continuous unauthorized disclosure of intellectual property, sensitive codebase components, and internal secrets via active webhook payloads.\nAn attacker capable of exploiting this vulnerability leverages previously established webhook subscriptions that persist despite privilege revocation, requiring no further active interaction once initial webhook placement has succeeded prior to access termination.\nThe primary exploitation requirement is the prior creation of a webhook by a collaborator whose access is subsequently removed without proper downstream cleanup of associated automation primitives.",
  "technicalDetails": "The root cause of the vulnerability stems from insufficient state synchronization and incomplete cleanup logic within the DeleteCollaboration function.\nWhen a collaborator's repository access is revoked, the access control layer updates repository permissions or removes the user association, but fails to cascade the deletion or deactivation down to associated integration primitives, specifically webhooks created during the collaborator's tenure.\nThe vulnerable component resides in the webhook management and collaborator lifecycle handling code, specifically within the execution scope of the DeleteCollaboration routine.\nExploitation occurs step-by-step through the following attack flow: First, a malicious or compromised collaborator with legitimate access provisions a webhook pointing to an external listener controlled by the attacker. Second, the repository administrator revokes the collaborator's access to the private repository, expecting all associated privileges and active integrations to terminate. Third, because the DeleteCollaboration function fails to purge or disable dependent webhooks, the webhook configuration remains active in the backend database and event dispatching queue. Finally, subsequent repository events trigger the orphaned webhook, resulting in the real-time transmission of private repository content to the attacker-controlled external endpoint indefinitely.\nAuthentication and privilege requirements involve initial legitimate access to configure repository webhooks, followed by the revocation event that highlights the flaw in cleanup logic.\nThe post-exploitation impact includes persistent, unauthorized telemetry and continuous data exfiltration of private repository assets, bypassing access control boundaries due to stale integration state."
}