How severe is GHSA-cpf9-ph2j-ccr9?

GHSA-cpf9-ph2j-ccr9 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-cpf9-ph2j-ccr9?

GHSA-cpf9-ph2j-ccr9 affects the following packages: github.com/openziti/zrok (Go), github.com/openziti/zrok/v2 (Go). Ecosystems affected: Go.

How do I fix GHSA-cpf9-ph2j-ccr9?

No patched version of github.com/openziti/zrok has shipped for GHSA-cpf9-ph2j-ccr9 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect GHSA-cpf9-ph2j-ccr9 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openziti/zrok. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-cpf9-ph2j-ccr9 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-cpf9-ph2j-ccr9?

O3 pinpoints whether GHSA-cpf9-ph2j-ccr9 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-cpf9-ph2j-ccr9 actively exploited in the wild?

No public exploit code has been indexed for GHSA-cpf9-ph2j-ccr9 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-cpf9-ph2j-ccr9 published, and has it been updated?

GHSA-cpf9-ph2j-ccr9 was published on April 16, 2026 and was last updated on June 25, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-cpf9-ph2j-ccr9

HIGH

GHSA-cpf9-ph2j-ccr9 is a high-severity (CVSS 7.5) vulnerability in github.com/openziti/zrok. O3 Security confirms whether GHSA-cpf9-ph2j-ccr9 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

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

Also known asCVE-2026-40303GO-2026-5329

Published

Apr 16, 2026

Updated

Jun 25, 2026

Affected

2 pkgs

Patched

1 / 2

Exploits

None indexed

Blast Radius

2 pkgs affected

🐹github.com/openziti/zrok🐹github.com/openziti/zrok/v2

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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

Affected Packages

2 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/openziti/zrok`	all versions	No fix
🐹Go	`github.com/openziti/zrok/v2`	all versions	2.0.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openziti/zrok. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
No patched version of github.com/openziti/zrok has shipped for GHSA-cpf9-ph2j-ccr9 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-cpf9-ph2j-ccr9 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-cpf9-ph2j-ccr9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

**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 preco

O3 Security · Impact-Aware SCA

Is GHSA-cpf9-ph2j-ccr9 in your dependencies?

O3 detects GHSA-cpf9-ph2j-ccr9 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works