Medium severity · published Jul 14, 2026
CVE-2026-45755
Symfony: Mailtrap Mailer Webhook Parser Never Verifies the X-Mt-Signature HMAC — Unauthenticated Webhook Event Injection
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 7.4.12 and 8.0.12, MailtrapRequestParser::doParse() received the configured webhook secret but ignored the X-Mt-Signature HMAC header, allowing unauthenticated POST requests to inject forged Mailtrap delivery, bounce, open, click, or spam events. This issue is fixed in versions 7.4.12 and 8.0.12.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
mailtrap-mailer · /mailtrap-mailer
>= 7.2.0, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor
SY
symfony · symfony
>= 7.2.0, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45755
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45755
Patch
https://github.com/symfony/symfony/commit/4e0467e4e182cf2e704a3d9e1bc1a6be65d52ab8
Product
https://github.com/symfony/symfony/releases/tag/v7.4.12
Product
https://github.com/symfony/symfony/releases/tag/v8.0.12
Patch
https://github.com/symfony/symfony/security/advisories/GHSA-59f3-vp2f-mp9w