zrok allows unauthenticated DoS via unbounded memory allocation in striped session cookie parsing
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-40303
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 22:24 UTC · Revision 1
Source evidence
zrok allows unauthenticated DoS via unbounded memory allocation in striped session cookie parsing
core-osv · Original sourcePublished 17 Apr 2026, 21:01 UTC
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.
osv:CVE-2026-40303
Complete source record
{
"id": "6ecf194e0fae7baa00ef5cfcb501b1195144a0ec5b50486df670d12b7f1ca052",
"url": "https://osv.dev/vulnerability/CVE-2026-40303",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "zrok allows unauthenticated DoS via unbounded memory allocation in striped session cookie parsing",
"summary": "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.",
"evidence": "osv:CVE-2026-40303",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-40303",
"aliases": [
"CVE-2026-40303",
"GHSA-cpf9-ph2j-ccr9",
"GO-2026-5329"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/openziti/zrok",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "69b9b8dd6d96be15639338414574aa5003f5f8f2"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "2.0.1"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "69b9b8dd6d96be15639338414574aa5003f5f8f2"
}
],
"source": "REFERENCES_TAG",
"original_tag": "v2.0.1"
},
{
"cpe": "cpe:2.3:a:netfoundry:zrok:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "2.0.1"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v1.1.11",
"v2.0.0",
"v2.0.0-rc9",
"v2.0.0-rc8",
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"v0.2.18",
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"v0.2.15",
"v0.2.14",
"v0.2.13",
"v0.2.12",
"v0.2.11",
"v0.2.10",
"v0.2.9",
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"v0.2.7",
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],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-40303.json"
}
}
],
"modified": "2026-10-28T02:30:40.187802616Z",
"provider": "osv",
"references": [
"https://github.com/openziti/zrok/releases/tag/v2.0.1",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40303.json",
"https://github.com/openziti/zrok/security/advisories/GHSA-cpf9-ph2j-ccr9",
"https://nvd.nist.gov/vuln/detail/CVE-2026-40303"
],
"provider_metadata": {
"cwe_ids": [
"CWE-400",
"CWE-789"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40303.json"
}
},
"related_cves": [
{
"value": "CVE-2026-40303",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 507577,
"published_at": "2026-04-17T21:01:51.899+00:00"
}