CVE-2026-28449: OpenClaw's Nextcloud Talk webhook replay could trigger duplicate inbound processing

Summary

When Nextcloud Talk webhook signing was valid, replayed requests could be accepted without durable replay suppression, allowing duplicate inbound processing after replay-window expiry or process restart.

Details

OpenClaw's Nextcloud Talk webhook path verified HMAC(secret, random + body) but previously lacked durable replay state tied to webhook events. This allowed replay of a previously valid signed request in some operational conditions.

The fix on main adds:

• persistent per-account replay dedupe for Nextcloud Talk webhook events,
• replay checks before webhook side effects (onMessage),
• backend-origin validation against configured account base URL (when configured).

Impact

A captured valid signed webhook request could be replayed to trigger duplicate inbound handling. This is an integrity/availability issue (duplicate actions/noise), scoped to deployments using Nextcloud Talk webhook integration.

Affected Packages / Versions

• Package: openclaw (npm)
• Affected: <= 2026.2.24
• Patched in release: 2026.2.25

Fix Commit(s)

• d512163d686ad6741783e7119ddb3437f493dbbc

Release Process Note

patched_versions is pre-set to the release (2026.2.25) so once npm release 2026.2.25 is published, advisory is now published.

OpenClaw thanks @aristorechina for reporting.