medium5.3
CVE-2026-48747
Symfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signature Algorithm Downgrade
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| composer | symfony/mailomat-mailer | >= 7.2.0, < 7.4.13 | 7.4.13 |
| composer | symfony/symfony | >= 7.2.0, < 7.4.13 | 7.4.13 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Sensiolabs | Symfony | from 7.2.0 before 7.4.13 from 8.0.0 before 8.0.13 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-rrj9-5q2j-4gvr
- https://github.com/symfony/symfony/security/advisories/GHSA-rrj9-5q2j-4gvr
- https://github.com/symfony/symfony/commit/bdfe9fe0d94d33dfaca0bc2fe0b00b54767b0c88
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mailomat-mailer/CVE-2026-48747.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-48747.yaml
- https://symfony.com/cve-2026-48747
- https://github.com/symfony/symfony/releases/tag/v7.4.13
- https://github.com/symfony/symfony/releases/tag/v8.0.13