CVE-2026-53840 | THREATINT

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.

PUBLISHED Reserved 2026-06-10 | Published 2026-06-16 | Updated 2026-06-16 | Assigner VulnCheck

MEDIUM: 6.0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

HIGH: 7.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

Problem types

Insufficiently Protected Credentials

Product status

Default status

unaffected

Any version before 2026.5.12

affected

2026.5.12 (semver)

unaffected

Credits

Edward-x (@YLChen-007) reporter

References

github.com/...enclaw/security/advisories/GHSA-rjxq-qqhf-8hwh (GitHub Security Advisory (GHSA-rjxq-qqhf-8hwh)) vendor-advisory

www.vulncheck.com/...-streamable-http-cross-origin-redirects (VulnCheck Advisory: OpenClaw < 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects) third-party-advisory

cve.org (CVE-2026-53840)

nvd.nist.gov (CVE-2026-53840)

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