CVE-2026-48747CWE-347CWE-757

Symfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signature Algorithm Downgrade

Medium · published July 14, 2026

CVSS v4.0
6.3
EPSS
0%
Percentile
15.1
In the wild
Unconfirmed
What it is

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 7.4.13 and 8.0.13, MailomatRequestParser::validateSignature() parsed X-MOM-Webhook-Signature as algo=signature and passed the request-selected algorithm to hash_hmac(), allowing a signature algorithm downgrade instead of enforcing Mailomat's documented SHA-256 webhook signature. This issue is fixed in versions 7.4.13 and 8.0.13.

The record
Technical detail
CVSS v4.0
6.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
EPSS
0.00247 · 15.1th percentile
Weaknesses
CWE-347 · Improper Verification of Cryptographic Signature; CWE-757 · Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
Published
2026-07-14T19:16Z
EPSS history
Timeline
  • 14 JUL 19:16Z
    Symfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signature Algorithm Downgrade
    cvelistv5