CVE-2026-34237 (GCVE-0-2026-34237)
Vulnerability from cvelistv5 – Published: 2026-03-31 15:40 – Updated: 2026-06-09 18:39
VLAI
EPSS
VEX
Title
MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)
Summary
MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 0.83.0, 1.0.1, and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 0.83.0, 1.0.1, and 1.1.1.
Severity
6.1 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-31 18:50 UTC
CWE
- CWE-942 - Permissive Cross-domain Policy with Untrusted Domains
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/java-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/java-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/java-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| modelcontextprotocol | java-sdk |
Affected:
>= 1.0.0, < 1.0.1
Affected: >= 1.1.0, < 1.1.1 Affected: < 0.18.3 |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-34237",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-31T18:50:15.819733Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-31T18:52:38.217Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "java-sdk",
"vendor": "modelcontextprotocol",
"versions": [
{
"status": "affected",
"version": "\u003e= 1.0.0, \u003c 1.0.1"
},
{
"status": "affected",
"version": "\u003e= 1.1.0, \u003c 1.1.1"
},
{
"status": "affected",
"version": "\u003c 0.18.3"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 0.83.0, 1.0.1, and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 0.83.0, 1.0.1, and 1.1.1."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-942",
"description": "CWE-942: Permissive Cross-domain Policy with Untrusted Domains",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-06-09T18:39:37.473Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22"
},
{
"name": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289"
},
{
"name": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525"
}
],
"source": {
"advisory": "GHSA-hv2w-8mjj-jw22",
"discovery": "UNKNOWN"
},
"title": "MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-34237",
"datePublished": "2026-03-31T15:40:01.070Z",
"dateReserved": "2026-03-26T16:22:29.034Z",
"dateUpdated": "2026-06-09T18:39:37.473Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-34237",
"date": "2026-09-22",
"epss": "0.00222",
"percentile": "0.13077"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"product": "java-sdk",
"vendor": "modelcontextprotocol",
"versions": [
{
"status": "affected",
"version": "\u003e= 1.0.0, \u003c 1.0.1"
},
{
"status": "affected",
"version": "\u003e= 1.1.0, \u003c 1.1.1"
},
{
"status": "affected",
"version": "\u003c 0.18.3"
}
]
}
],
"source": "security-advisories@github.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:lfprojects:mcp_java_sdk:*:*:*:*:*:*:*:*",
"matchCriteriaId": "25694CAC-2051-4746-9F09-053F94A30507",
"versionEndExcluding": "1.0.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:lfprojects:mcp_java_sdk:1.1.0:*:*:*:*:*:*:*",
"matchCriteriaId": "5E0E201B-2A7F-49EE-A48E-6FF7D1AD3A7B",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 0.83.0, 1.0.1, and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 0.83.0, 1.0.1, and 1.1.1."
},
{
"lang": "es",
"value": "MCP Java SDK es el SDK oficial de Java para servidores y clientes del Protocolo de Contexto de Modelo. Antes de las versiones 1.0.1 y 1.1.1, existe una vulnerabilidad CORS de comod\u00edn codificado. Este problema ha sido parcheado en las versiones 1.0.1 y 1.1.1."
}
],
"id": "CVE-2026-34237",
"lastModified": "2026-07-24T20:10:00.147",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 2.7,
"source": "security-advisories@github.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-34237",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-31T18:50:15.819733Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-03-31T16:16:32.923",
"references": [
{
"source": "security-advisories@github.com",
"tags": [
"Patch"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289"
},
{
"source": "security-advisories@github.com",
"tags": [
"Patch"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525"
},
{
"source": "security-advisories@github.com",
"tags": [
"Mitigation",
"Vendor Advisory"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22"
}
],
"sourceIdentifier": "security-advisories@github.com",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-942"
}
],
"source": "security-advisories@github.com",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"current_release_date": "2026-06-09T20:59:39+00:00",
"cve": "CVE-2026-34237",
"id": "CVE-2026-34237",
"initial_release_date": "2026-01-01T00:00:00+00:00",
"product_status:known_not_affected": "1",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34237.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-34237",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-31T18:50:15.819733Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-31T18:50:16.963Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "java-sdk",
"vendor": "modelcontextprotocol",
"versions": [
{
"status": "affected",
"version": "\u003e= 1.0.0, \u003c 1.0.1"
},
{
"status": "affected",
"version": "\u003e= 1.1.0, \u003c 1.1.1"
},
{
"status": "affected",
"version": "\u003c 0.18.3"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 0.83.0, 1.0.1, and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 0.83.0, 1.0.1, and 1.1.1."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-942",
"description": "CWE-942: Permissive Cross-domain Policy with Untrusted Domains",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-06-09T18:39:37.473Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22"
},
{
"name": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289"
},
{
"name": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525"
}
],
"source": {
"advisory": "GHSA-hv2w-8mjj-jw22",
"discovery": "UNKNOWN"
},
"title": "MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-34237",
"datePublished": "2026-03-31T15:40:01.070Z",
"dateReserved": "2026-03-26T16:22:29.034Z",
"dateUpdated": "2026-06-09T18:39:37.473Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…