OpenClaw < 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects
Summary
| CVE | CVE-2026-53840 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-16 19:17:00 UTC |
| Updated | 2026-06-17 20:31:29 UTC |
| Description | OpenClaw before 2026.5.12 contains an information disclosure vulnerability in streamable-http MCP servers that forwards operator-configured custom headers during cross-origin redirects. Attackers controlling or compromising an MCP endpoint can redirect requests to exfiltrate sensitive headers like API keys or tenant-routing credentials to attacker-controlled origins. |
Risk And Classification
Primary CVSS: v4.0 6 MEDIUM from [email protected]
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.002230000 probability, percentile 0.127320000 (date 2026-06-18)
Problem Types: CWE-522 | CWE-522 Insufficiently Protected Credentials
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 6 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 6 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N |
| 3.1 | [email protected] | Secondary | 7.1 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N |
| 3.1 | CNA | CVSS | 7.1 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
PresentPrivileges Required
LowUser Interaction
NoneConfidentiality
HighIntegrity
LowAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
LowAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Openclaw | Openclaw | All | All | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta1 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta2 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta3 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta4 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta5 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta6 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta7 | All | All |
| Application | Openclaw | Openclaw | 2026.5.12 | beta8 | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.vulncheck.com/advisories/openclaw-custom-header-leakage-via-mcp-streamable-... | [email protected] | www.vulncheck.com | Third Party Advisory |
| github.com/openclaw/openclaw/security/advisories/GHSA-rjxq-qqhf-8hwh | [email protected] | github.com | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Edward-x (@YLChen-007) (en)
There are currently no legacy QID mappings associated with this CVE.