CVE-2026-48747

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

MEDIUM

5.3

CVSS Score

Published: July 14, 2026 at 07:16 PM UTC

Updated: July 15, 2026 at 03:16 PM UTC

3 products affected across 2 vendorsSymfonySymfonyMailomat Mailer

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Severity

MEDIUM5.3

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Symfony · Sensiolabsdrupal

95%

7.2.0 ≤ v < 7.4.138.0.0 ≤ v < 8.0.13

Affected range stops below 7.4.13, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.0.13, so it looks safe — our inference, not a vendor statement

Mailomat Mailer · Symfony

60%

v < 7.4.12v < 8.0.13

Affected range stops below 7.4.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.0.13, so it looks safe — our inference, not a vendor statement

Symfony · Symfonycomposer

60%

v < 7.4.12v < 8.0.13

Affected range stops below 7.4.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.0.13, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (4)

x_refsource_CONFIRMPatchVendor Advisory

Source: cverecord

https://github.com/symfony/symfony/security/advisories/GHSA-rrj9-5q2j-4gvr

x_refsource_MISCPatch

Source: cverecord

https://github.com/symfony/symfony/commit/bdfe9fe0d94d33dfaca0bc2fe0b00b54767b0c88

x_refsource_MISCProductRelease Notes

Source: cverecord

https://github.com/symfony/symfony/releases/tag/v7.4.13

x_refsource_MISCProductRelease Notes

Source: cverecord

https://github.com/symfony/symfony/releases/tag/v8.0.13

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUM[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-347CWE-757

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