CVE-2026-45755Network attack vector

Unauthenticated webhook event injection via ignored HMAC

Published Jul 14, 2026 · Updated Jul 14, 2026

Authentication bypass in Symfony Mailtrap Mailer Bridge before 7.4.12 and 8.0.12 allows remote attackers to inject forged events. MailtrapRequestParser::doParse() accepts the configured secret but decodes and returns the POST body without reading or verifying the X-Mt-Signature HMAC header. This requires an application to expose the Mailtrap webhook endpoint and enables forged events to corrupt suppression lists or falsify delivery metrics.

CVSS severity6.9
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Symfony Mailtrap Mailer Bridge before 7.4.12 and 8.0.12 allows remote attackers to inject forged events. MailtrapRequestParser::doParse() accepts the configured secret but decodes and returns the POST body without reading or verifying the X-Mt-Signature HMAC header. This requires an application to expose the Mailtrap webhook endpoint and enables forged events to corrupt suppression lists or falsify delivery metrics.

The record

CVE
CVE-2026-45755
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Symfony
Product
Mailtrap Mailer Bridge
Classifications
CWE-306, CWE-347, T1190, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 7.2.0, < 7.4.12
  2. Affected versionversion=>= 8.0.0-BETA1, < 8.0.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Symfony · Mailtrap Mailer Bridgeversion=>= 7.2.0, < 7.4.12; version=>= 8.0.0-BETA1, < 8.0.12
Symfony · Symfonyversion=>= 7.2.0, < 7.4.12; version=>= 8.0.0-BETA1, < 8.0.12

Published CVSS scores

6.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
CWE-347Improper Verification of Cryptographic Signature
T1190Exploit Public-Facing Application
T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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