Vulnerability · Published Jun 16, 2026 · Assigned by VulnCheck

CVE-2026-53840OpenClaw < 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects

High 7.1

In plain English

A high-severity security flaw in OpenClaw from OpenClaw. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.1High

Exploit odds (30 days)0.2%top 87.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	openclaw	2026.5.12	GHSA-rjxq-qqhf-8hwh

Affected products (as reported)

Vendor	Product	Versions
OpenClaw	OpenClaw	0 – before 2026.5.12

Weakness: CWE-522 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

References

GitHub Security Advisory (GHSA-rjxq-qqhf-8hwh) vendor-advisory
VulnCheck Advisory: OpenClaw < 2026.5.12 - Custom Header Leakage via MCP Streamable HTTP Cross-Origin Redirects third-party-advisory