zrok: Unauthenticated DoS via unbounded memory allocation in striped session cookie parsing

Description

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

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-04-16 21:09:08 UTC
Updated
2026-04-24 20:48:50 UTC
GitHub reviewed
2026-04-16 21:09:08 UTC
NVD published
2026-04-17

EPSS Score

Score Percentile
0.03% 8.40%

CVSS Scores

Base score Version Severity Vector
7.5 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

CWEs

CWE id Name
CWE-400 Uncontrolled Resource Consumption
CWE-789 Memory Allocation with Excessive Size Value

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/openziti/zrok <= 1.1.11
go github.com/openziti/zrok/v2 < 2.0.1 2.0.1

References

cvelogic Threat Intelligence