{"id":"CVE-2026-53840","aliases":["EUVD-2026-37142","GHSA-rjxq-qqhf-8hwh","GHSA-x7cf-6gp3-q5f8"],"status":"published","title":"OpenClaw \u003c 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects","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.","severity":{"version":"4.0","score":6,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00223,"percentile":0.1305,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-200","CWE-522"],"published":"2026-06-16T18:04:53Z","modified":"2026-10-28T02:30:44Z","fixes":[{"ecosystem":"npm","package":"openclaw","fixed_in":["2026.5.12"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"openclaw","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2026.5.12"}]}]},{"source":"osv","ecosystem":"npm","package":"openclaw","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2026.5.12"}]}]}],"products":[{"vendor":"openclaw","product":"openclaw"}],"references":[{"url":"https://github.com/openclaw/openclaw/security/advisories/GHSA-rjxq-qqhf-8hwh","tags":["vendor-advisory","Vendor Advisory","advisory","web"]},{"url":"https://www.vulncheck.com/advisories/openclaw-custom-header-leakage-via-mcp-streamable-http-cross-origin-redirects","tags":["third-party-advisory","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53840","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-rjxq-qqhf-8hwh"},{"url":"https://github.com/advisories/GHSA-x7cf-6gp3-q5f8"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53840.json","tags":["advisory"]},{"url":"https://github.com/openclaw/openclaw","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-53840","title":"OpenClaw \u003c 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects","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.","status":"published","published":"2026-06-16T18:04:53.345Z","modified":"2026-06-16T18:51:19.624Z","cvss":[{"version":"4.0","score":6,"vector":"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","level":"medium","assessor":"cna"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-522"],"updated_at":"2026-11-02T14:20:00.11477Z"}],"euvd":[{"id":"EUVD-2026-37142","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.","status":"published","published":"2026-06-16T18:04:53Z","modified":"2026-06-16T18:51:19Z","cvss":[{"version":"4.0","score":6,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T18:20:39.851172Z"}],"ghsa":[{"id":"GHSA-rjxq-qqhf-8hwh","title":"OpenClaw: MCP Streamable HTTP redirects could forward configured custom headers to another origin","description":"### Summary\n\nOpenClaw supports remote MCP Streamable HTTP servers with operator-configured custom headers. In affected releases, those headers could be forwarded when the MCP endpoint responded with a cross-origin redirect.\n\nThis issue is limited to configured MCP Streamable HTTP servers that use custom headers. It does not expose unrelated OpenClaw credentials.\n\n### Affected configurations\n\nThis affects deployments where an MCP server is configured with:\n\n- `transportType: \"streamable-http\"`\n- sensitive custom headers under `mcp.servers.*.headers`\n- an MCP endpoint that is malicious, compromised, or able to redirect to another origin\n\n### Impact\n\nCustom MCP headers, such as API keys or tenant-routing headers, could be sent to the redirect target. The exposed credential scope depends on the header the operator configured for that MCP server.\n\n### Patched Versions\n\nThe first stable patched version is `2026.5.12`.\n\n### Mitigations\n\nUpgrade to `openclaw@2026.5.8` or later. Before upgrading, avoid custom MCP headers with servers you do not fully trust, and rotate any MCP-specific credentials that may have been exposed by a redirecting endpoint.","status":"published","published":"2026-06-17T17:55:06Z","modified":"2026-06-17T17:55:08Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:40:28.438722Z"},{"id":"GHSA-x7cf-6gp3-q5f8","title":"Duplicate Advisory: MCP Streamable HTTP redirects could forward configured custom headers to another origin","description":"## Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-rjxq-qqhf-8hwh. This link is maintained to preserve external references.\n\n## Original Description\nOpenClaw 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.","status":"withdrawn","published":"2026-06-16T21:31:57Z","modified":"2026-06-17T17:54:48Z","cvss":[{"version":"4.0","score":6,"vector":"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","level":"medium"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-522"],"updated_at":"2026-11-02T14:40:28.438722Z"}],"nvd":[{"id":"CVE-2026-53840","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.","status":"published","published":"2026-06-16T19:17:00.863Z","modified":"2026-06-17T20:31:29.327Z","cvss":[{"version":"4.0","score":6,"vector":"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","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-522"],"updated_at":"2026-11-02T14:12:24.19758Z"}],"osv":[{"id":"CVE-2026-53840","title":"OpenClaw \u003c 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects","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.","status":"published","published":"2026-06-16T18:04:53.345Z","modified":"2026-10-28T02:30:44.28939318Z","cvss":[{"version":"4.0","score":6,"vector":"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","level":"medium"}],"cwes":["CWE-522"],"updated_at":"2026-11-02T15:45:08.132336Z"},{"id":"GHSA-rjxq-qqhf-8hwh","title":"OpenClaw: MCP Streamable HTTP redirects could forward configured custom headers to another origin","description":"### Summary\n\nOpenClaw supports remote MCP Streamable HTTP servers with operator-configured custom headers. In affected releases, those headers could be forwarded when the MCP endpoint responded with a cross-origin redirect.\n\nThis issue is limited to configured MCP Streamable HTTP servers that use custom headers. It does not expose unrelated OpenClaw credentials.\n\n### Affected configurations\n\nThis affects deployments where an MCP server is configured with:\n\n- `transportType: \"streamable-http\"`\n- sensitive custom headers under `mcp.servers.*.headers`\n- an MCP endpoint that is malicious, compromised, or able to redirect to another origin\n\n### Impact\n\nCustom MCP headers, such as API keys or tenant-routing headers, could be sent to the redirect target. The exposed credential scope depends on the header the operator configured for that MCP server.\n\n### Patched Versions\n\nThe first stable patched version is `2026.5.12`.\n\n### Mitigations\n\nUpgrade to `openclaw@2026.5.8` or later. Before upgrading, avoid custom MCP headers with servers you do not fully trust, and rotate any MCP-specific credentials that may have been exposed by a redirecting endpoint.","status":"published","published":"2026-06-17T17:55:06Z","modified":"2026-06-17T18:11:28.897834Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:46:55.877614Z"},{"id":"GHSA-x7cf-6gp3-q5f8","title":"Duplicate Advisory: MCP Streamable HTTP redirects could forward configured custom headers to another origin","description":"## Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-rjxq-qqhf-8hwh. This link is maintained to preserve external references.\n\n## Original Description\nOpenClaw 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.","status":"withdrawn","published":"2026-06-16T21:31:57Z","modified":"2026-09-10T03:51:09.674672288Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"high"},{"version":"4.0","score":6,"vector":"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","level":"medium"}],"cwes":["CWE-522"],"updated_at":"2026-11-02T15:46:59.484835Z"}]}}