CVE-2026-40303

zrok allows unauthenticated DoS via unbounded memory allocation in striped session cookie parsing

HIGH
7.5
CVSS Score
Published: April 17, 2026 at 09:01 PM UTC
Updated: June 17, 2026 at 10:44 AM UTC
2 products affected across 2 vendorsZrokZrok

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Severity
HIGH7.5
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.0.1
v < 2.0.1
Affected range stops below 2.0.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/openziti/zrok/security/advisories/GHSA-cpf9-ph2j-ccr9
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/openziti/zrok/releases/tag/v2.0.1

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400CWE-789

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