Fix webhook toleranceSeconds unit mismatch - #393
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The ts value in the x-signature header is Unix time in seconds, but the tolerance check was comparing it directly against Instant.toEpochMilli(), causing valid webhooks with recent timestamps to be rejected as out of tolerance. Multiply ts by 1000 to convert to milliseconds before the comparison. Updated existing tolerance tests to use getEpochSecond() consistently and added a dedicated test covering the seconds-based path.
Diego Barajas (barajas-d)
approved these changes
Aug 3, 2026
2 tasks
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Summary
Fixes two bugs in WebhookSignatureValidator reported in issues #458 and #459:
Bug #458 — toleranceSeconds comparing seconds against milliseconds
The `ts` value in the `x-signature` header is in seconds (e.g. `1704908010`), but the clock was read in milliseconds. This made any `toleranceSeconds` value effectively reject every legitimate webhook notification.
Fix: Convert `ts` to milliseconds before computing drift.
Bug #459 — RangeError on multibyte v1 hash (Node.js only)
`constantTimeEquals` compared string `length` (characters) but `Buffer.from()` operates on bytes. A 64-character v1 with one multibyte character has 65 bytes, passing the guard and throwing `RangeError` instead of `InvalidWebhookSignatureError`.
Fix: Use `Buffer.byteLength()` in the length guard.
Test plan
Closes #458, Closes #459
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