Medium 6.3Published Jul 14, 2026

CVE-2026-48747Symfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signature Algorithm Downgrade

Updated under an hour ago (Oct 26, 2026, 4:30 AM ET)

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It affects symfony and 2 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for symfony

Exploited in the last 30 days

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.

CVSS: 6.3 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-347, CWE-757
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

symfony symfony symfony:symfony (from the name)	from 7.2.0, < 7.4.12; from 8.0.0-BETA1, < 8.0.13	CNA record
symfony mailomat-mailer symfony:mailomat_mailer (from the name)	from 7.2.0, < 7.4.12; from 8.0.0-BETA1, < 8.0.13	CNA record
sensiolabs symfony sensiolabs:symfony	from 7.2.0 before 7.4.13; from 8.0.0 before 8.0.13	NVD

References

https://github.com/symfony/symfony/security/advisories/GHSA-rrj9-5q2j-4gvrx-refsource-confirm, patch, vendor-advisory
https://github.com/symfony/symfony/commit/bdfe9fe0d94d33dfaca0bc2fe0b00b54767b0c88x-refsource-misc, patch
https://github.com/symfony/symfony/releases/tag/v7.4.13x-refsource-misc, product, release-notes
https://github.com/symfony/symfony/releases/tag/v8.0.13x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.