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Verify GitHub webhook signatures with SHA-256 instead of SHA-1 #314

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Merged
fabpot merged 1 commit into from
Sep 21, 2026
Merged

Verify GitHub webhook signatures with SHA-256 instead of SHA-1 #314

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8 changes: 2 additions & 6 deletions src/Service/GitHubRequestHandler.php
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ public function handle(Request $request): array
throw new AccessDeniedHttpException(sprintf('No webhook secret configured for repository "%s".', $repository->getFullName()));
}

$signature = $request->headers->get('X-Hub-Signature');
$signature = $request->headers->get('X-Hub-Signature-256');
if (null === $signature || '' === $signature) {
throw new AccessDeniedHttpException('The request is not secured.');
}
Expand Down Expand Up @@ -92,10 +92,6 @@ public function handle(Request $request): array

private function authenticate(string $hash, string $key, string $data): bool
{
if (!extension_loaded('hash')) {
throw new \RuntimeException('"hash" extension is needed to check request signature.');
}

return hash_equals($hash, 'sha1='.hash_hmac('sha1', $data, $key));
return hash_equals($hash, 'sha256='.hash_hmac('sha256', $data, $key));
}
}
6 changes: 3 additions & 3 deletions tests/Controller/WebhookControllerTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ public function testUnsignedRequestIsRejected()
public function testRequestWithInvalidSignatureIsRejected()
{
$body = file_get_contents(__DIR__.'/../webhook_examples/issue_comment.created.json');
$this->postWebhook('issue_comment', $body, 'sha1='.hash_hmac('sha1', $body, 'not-the-configured-secret'));
$this->postWebhook('issue_comment', $body, 'sha256='.hash_hmac('sha256', $body, 'not-the-configured-secret'));

$this->assertResponseStatusCodeSame(403);
}
Expand All @@ -74,7 +74,7 @@ private function postWebhook(string $eventHeader, string $body, ?string $signatu
{
$server = ['HTTP_X-Github-Event' => $eventHeader];
if (null !== $signature) {
$server['HTTP_X-Hub-Signature'] = $signature;
$server['HTTP_X-Hub-Signature-256'] = $signature;
}

$this->client->request('POST', '/webhooks/github', [], [], $server, $body);
Expand All @@ -86,7 +86,7 @@ private function sign(string $body): string
->getRepository('carsonbot-playground/symfony')
->getSecret();

return 'sha1='.hash_hmac('sha1', $body, $secret);
return 'sha256='.hash_hmac('sha256', $body, $secret);
}

/**
Expand Down
18 changes: 16 additions & 2 deletions tests/Service/GitHubRequestHandlerTest.php
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Expand Up @@ -36,11 +36,25 @@ public function testSignedRequestIsAccepted()
$handler = $this->createHandler(['carsonbot-playground/symfony' => ['secret' => 'a_secret']]);
$body = $this->createBody();

$responseData = $handler->handle($this->createRequest($body, 'sha1='.hash_hmac('sha1', $body, 'a_secret')));
$responseData = $handler->handle($this->createRequest($body, 'sha256='.hash_hmac('sha256', $body, 'a_secret')));

$this->assertSame(['unsupported_action' => 'issues'], $responseData);
}

public function testLegacySha1SignatureIsRejected()
{
$handler = $this->createHandler(['carsonbot-playground/symfony' => ['secret' => 'a_secret']]);
$body = $this->createBody();

$request = $this->createRequest($body);
$request->headers->set('X-Hub-Signature', 'sha1='.hash_hmac('sha1', $body, 'a_secret'));

$this->expectException(AccessDeniedHttpException::class);
$this->expectExceptionMessage('The request is not secured.');

$handler->handle($request);
}

/**
* @param array<string, array{secret?: string}> $repositories
*/
Expand All @@ -53,7 +67,7 @@ private function createRequest(string $body, ?string $signature = null): Request
{
$server = ['HTTP_X-Github-Event' => 'issues'];
if (null !== $signature) {
$server['HTTP_X-Hub-Signature'] = $signature;
$server['HTTP_X-Hub-Signature-256'] = $signature;
}

return Request::create('/webhooks/github', 'POST', [], [], [], $server, $body);
Expand Down
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