GHSA-59f3-vp2f-mp9w
Suggest an improvement- Source
- https://github.com/advisories/GHSA-59f3-vp2f-mp9w
- Import Source
- https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-59f3-vp2f-mp9w/GHSA-59f3-vp2f-mp9w.json
- JSON Data
- https://api.osv.dev/v1/vulns/GHSA-59f3-vp2f-mp9w
- Aliases
-
- CVE-2026-45755
- Published
- 2026-05-28T17:33:47Z
- Modified
- 2026-05-28T17:45:08.714389348Z
- Severity
-
- 6.6 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U CVSS Calculator
- Summary
- Symfony's Mailtrap Mailer Webhook Parser Never Verifies the X-Mt-Signature HMAC — Unauthenticated Webhook Event Injection
- Details
-
Description
The Mailtrap mailer bridge ships a webhook request parser used to authenticate and decode the event callbacks Mailtrap POSTs to an application's webhook endpoint. Its
doParse(Request $request, #[\SensitiveParameter] string $secret)method receives the configured webhook secret but never reads it; it decodes and returns the payload unconditionally, ignoring theX-Mt-SignatureHMAC header Mailtrap sends with each request.As a result, an application that wires up the Mailtrap webhook endpoint accepts any POST to that URL, even when a signing secret is configured (the recommended setup). An attacker who knows the endpoint exists can submit forged event payloads, fake delivery / bounce / open / click / spam events, leading to suppression-list corruption, delivery-metrics fraud, etc.
Resolution
MailtrapRequestParser::doParse()now requires and verifies theX-Mt-Signatureheader, an HMAC-SHA256 of the raw request body keyed with the configured secret, before decoding the payload, using a constant-time comparison.When no secret is configured the behaviour is unchanged: signature verification remains opt-in, but it is now actually enforced once opted in.
The patch for this issue is available here for branch 7.4.
Credits
Symfony would like to thank Himanshu Anand for reporting the issue and Alexandre Daubois providing the fix.
- Database specific
{ "cwe_ids": [ "CWE-306", "CWE-347" ], "github_reviewed": true, "nvd_published_at": null, "github_reviewed_at": "2026-05-28T17:33:47Z", "severity": "MODERATE" }- References
-
- https://github.com/symfony/symfony/security/advisories/GHSA-59f3-vp2f-mp9w
- https://github.com/symfony/symfony/commit/4e0467e4e182cf2e704a3d9e1bc1a6be65d52ab8
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mailtrap-mailer/CVE-2026-45755.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45755.yaml
- https://github.com/symfony/symfony
- https://symfony.com/cve-2026-45755
Affected packages
Packagist / symfony/mailtrap-mailer
Package
- Name
- symfony/mailtrap-mailer
- Purl
- pkg:composer/symfony%2Fmailtrap-mailer
Packagist / symfony/mailtrap-mailer
Package
- Name
- symfony/mailtrap-mailer
- Purl
- pkg:composer/symfony%2Fmailtrap-mailer
Packagist / symfony/symfony
Package
- Name
- symfony/symfony
- Purl
- pkg:composer/symfony%2Fsymfony
Affected versions
v7.*
Packagist / symfony/symfony
Package
- Name
- symfony/symfony
- Purl
- pkg:composer/symfony%2Fsymfony