CVE-2026-28478

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.

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.

Credits

Thanks @vincentkoc for reporting.

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

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2026-28478 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2026.2.13); upgrading removes the vulnerable code path.

Kodem intelligence

Upgrade to the first release containing this patch.

1. What is CVE-2026-28478? CVE-2026-28478 is a high-severity uncontrolled resource consumption vulnerability in openclaw (npm), affecting versions < 2026.2.13. It is fixed in 2026.2.13. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
2. How severe is CVE-2026-28478? CVE-2026-28478 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-28478?
   • openclaw (npm) (versions < 2026.2.13)
   • clawdbot (npm) (versions <= 2026.1.24-3)
4. Is there a fix for CVE-2026-28478? Yes. CVE-2026-28478 is fixed in 2026.2.13. Upgrade to this version or later.
5. Is CVE-2026-28478 exploitable, and should I be worried? Whether CVE-2026-28478 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-28478 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-28478? Upgrade openclaw to 2026.2.13 or later.