CVE-2026-57122
The WhatsApp and Linear bot adapters verify the inbound webhook HMAC signature only
when a secret is configured. When the secret environment variable is unset — the
default on a fresh install and common in development — verification is skipped entirely
and the webhook body is parsed and dispatched as a genuine, trusted event. A remote,
unauthenticated attacker who can reach the bot's webhook endpoint can inject arbitrary
platform events.
Affected code:
WhatsApp - src/praisonai/praisonai/bots/whatsapp.py
- init (line 108): self._app_secret = app_secret or os.environ.get("WHATSAPP_APP_SECRET", "") -> defaults to ""
- route (line 246): app.router.add_post(self._webhook_path, self._handle_webhook) -> default path "/webhook"
- _handle_webhook (lines 585-595): if self._app_secret: gates the ENTIRE check; when falsy the body is
json.loads()'d and dispatched to _process_webhook_data() with no verification.
Linear - src/praisonai/praisonai/bots/linear.py
- init (line 86): self._signing_secret = signing_secret or os.environ.get("LINEAR_WEBHOOK_SECRET", "") -> ""
- _handle_webhook (lines 244-248): same if self._signing_secret: fail-open guard.
- start() (lines 169-170): only logs a warning; does not fail closed.
The _verify_signature implementations themselves are correct (constant-time HMAC-SHA256);
the defect is that verification is bypassed when the secret is absent.
Impact:
- WhatsApp: attacker POSTs a crafted Meta Cloud API payload spoofing any sender and message
text; injected into agent sessions and processed as a real user message (prompt injection,
unauthorized agent/command invocation, contact impersonation).
- Linear: attacker POSTs forged AgentSession / Comment events, causing the agent to act on and
comment on issues no legitimate event referenced.
The webhook routes require no other authentication, so exploitation needs only network
reachability.
Proof of concept (bot started without the secret - the default):
curl -X POST http://VICTIM:PORT/webhook \
-H '
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