zrok is software for sharing web services, files, and network resources. Prior to version 2.0.1, endpoints.GetSessionCookie parses an attacker-supplied cookie chunk count and calls make([]string, count) with no upper bound before any token validation occurs. The function is reached on every request to an OAuth-protected proxy share, allowing an unauthenticated remote attacker to trigger gigabyte-scale heap allocations per request, leading to process-level OOM termination or repeated goroutine panics. Both publicProxy and dynamicProxy are affected. Version 2.0.1 patches the issue.

Affected: Go: github.com/openziti/zrok, Go: github.com/openziti/zrok/v2

**Summary** endpoints.GetSessionCookie parses an attacker-supplied cookie chunk count and calls make([]string, count) with no upper bound before any token validation occurs. The function is reached on every request to an OAuth-protected proxy share, allowing an unauthenticated remote attacker to trigger gigabyte-scale heap allocations per request, leading to process-level OOM termination or repeated goroutine panics. Both publicProxy and dynamicProxy are affected.

- Attack Vector: Network — exploitable via a single HTTP request with a crafted Cookie header. - Attack Complexity: Low — no preconditions or chaining required; the attacker only needs to know the cookie name (publicly derivable from any OAuth redirect). - Privileges Required: None — reached before JWT validation or any authentication check. - User Interaction: None. - Scope: Unchanged — impact is confined to the affected proxy process. - Confidentiality Impact: None. - Integrity Impact: None.

Availability Impact: High — sustained or concurrent requests cause OOM process termination, taking down the proxy for all users of all shares it serves.

**Affected Components** - endpoints/oauthCookies.go — GetSessionCookie (line 81) - endpoints/publicProxy/authOAuth.go — handleOAuth (line 50) — call site, pre-auth - endpoints/dynamicProxy/cookies.go — getSessionCookie (line 29) — call site