Improper Verification of Cryptographic Signature Affecting symfony/symfony package, versions <7.4.13>=8.0.0-BETA1, <8.0.13
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-SYMFONYSYMFONY-16895618
- published27 May 2026
- disclosed27 May 2026
- creditAlwaleed Alshamari, Essam Alanazi, KEJJ0
Introduced: 27 May 2026
CVE-2026-48747 (opens in a new tab)How to fix?
Upgrade symfony/symfony to version 7.4.13, 8.0.13 or higher.
Overview
symfony/symfony is a PHP framework for web applications and a set of reusable PHP components.
Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the webhook request parser. The validateSignature() method extracts the X-MOM-Webhook-Signature header and passes the user-supplied cryptographic algorithm directly into PHP's hash_hmac() function. This algorithm confusion allowed an attacker to dictate the hashing mechanism used to verify the webhook's authenticity. By supplying a weak, outdated cryptographic primitive (such as MD4 or MD5), an attacker could exploit known cryptanalysis weaknesses to forge valid HMAC signatures and bypass webhook authentication checks. The patch resolves this by strictly enforcing the sha256 algorithm and rejecting any other user-supplied algorithms.