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CVE-2026-45755: Symfony's Mailtrap Mailer Webhook Parser Never Verifies the X-Mt-Signature HMAC — Unauthenticated Webhook Event Injection

medium Affects symfony/mailtrap-mailer, symfony/symfony. Feed 2026.10.29.4, updated 2026-10-29; published ; advisory modified .

Symfony's Mailtrap Mailer Webhook Parser Never Verifies the X-Mt-Signature HMAC — Unauthenticated Webhook Event Injection

Package
symfony/mailtrap-mailer Composer
Affected versions
>=7.2.0 and <7.4.12 or >=8.0.0 and <8.0.12 or >=7.2.0 and <7.3.0 or >=7.3.0 and <7.4.0 or >=7.4.0 and <7.4.12
Fixed in
7.4.12, 8.0.12
Severity
medium
Exploitation
not on CISA KEV · EPSS 0% (18.9th percentile)
Published
2026-05-28
Source
osv.dev

References

Symfony's Mailtrap Mailer Webhook Parser Never Verifies the X-Mt-Signature HMAC — Unauthenticated Webhook Event Injection

Package
symfony/symfony Composer
Affected versions
>=7.2.0 and <7.4.12 or >=8.0.0 and <8.0.12 or >=7.2.0 and <7.3.0 or >=7.3.0 and <7.4.0 or >=7.4.0 and <7.4.12
Fixed in
7.4.12, 8.0.12
Severity
medium
Exploitation
not on CISA KEV · EPSS 0% (18.9th percentile)
Published
2026-05-28
Source
osv.dev

References

CWE-306CWE-347
NVD recordsymfony/mailtrap-mailer advisoriessymfony/symfony advisories

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