CVE-2026-28478: OpenClaw affected by denial of service via unbounded webhook request body buffering

Summary

Multiple webhook handlers accepted and buffered request bodies without a strict unified byte/time limit. A remote unauthenticated attacker could send oversized payloads and cause memory pressure, degrading availability.

Details

Affected packages:

• openclaw (npm): <2026.2.12
• clawdbot (npm): <=2026.1.24-3

Root cause:

• Webhook code paths buffered request payloads without consistent maxBytes + timeoutMs enforcement.
• Some SDK-backed handlers parse request bodies internally and needed stream-level guards.

Attack shape:

• Send very large JSON payloads or slow/incomplete uploads to webhook endpoints.
• Observe elevated memory usage and request handler pressure.

Impact

Remote unauthenticated availability impact (DoS) via request body amplification/memory pressure.

Patch details (implemented)

• Added shared bounded request-body helper in src/infra/http-body.ts.
• Exported helper in src/plugin-sdk/index.ts for extension reuse.
• Migrated webhook body readers to shared helper for:
• LINE
• Nextcloud Talk
• Google Chat
• Zalo
• BlueBubbles
• Nostr profile HTTP
• Voice-call
• Gateway hooks
• Added stream guards for SDK handlers that parse request bodies internally:
• Slack
• Telegram
• Feishu
• Added explicit Express JSON body limit handling for MS Teams webhook path.
• Standardized failure responses:
• 413 Payload Too Large
• 408 Request Timeout

Tests

• Added regression tests:
• src/infra/http-body.test.ts
• src/line/monitor.read-body.test.ts
• extensions/nextcloud-talk/src/monitor.read-body.test.ts
• Focused webhook/security test suite passes for patched paths.

Remediation

Upgrade to the first release containing this patch.

Credits

Thanks @vincentkoc for reporting.