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fix: reject non-ASCII webhook signatures without raising #269

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fix: reject non-ASCII webhook signatures without raising #269

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3 changes: 3 additions & 0 deletions flagsmith/webhooks.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,5 +37,8 @@ def verify_signature(
:param shared_secret: The shared secret configured for this specific webhook.
:return: True if the signature is valid, False otherwise.
"""
if not received_signature.isascii():
return False

expected_signature = generate_signature(request_body, shared_secret)
return hmac.compare_digest(expected_signature, received_signature)
8 changes: 8 additions & 0 deletions tests/test_webhooks.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
import json

import pytest

from flagsmith.webhooks import generate_signature, verify_signature


Expand Down Expand Up @@ -48,3 +50,9 @@ def test_verify_signature_invalid() -> None:
received_signature="bad",
shared_secret="?",
)


@pytest.mark.parametrize("signature", ["é", "🔒", "a" * 63 + "é", "\ud800"])
@pytest.mark.parametrize("body", ["{}", b"{}"])
def test_verify_signature_rejects_non_ascii(signature: str, body: str | bytes) -> None:
assert verify_signature(body, signature, "secret") is False