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GHSA-xx3c-qf5g-hc39

MediumCVSS 6.2 / 10
Published May 27, 2026·Last modified May 27, 2026
Affected Components(0)

No affected components available

Description

Description

Symfony Mailer selects a transport via the MAILER_DSN environment variable / configuration (e.g. smtp://..., sendmail://..., native://default). SendmailTransport invokes the local sendmail binary and supports two modes: -bs (speak SMTP over stdin: the default) and -t (read the message on stdin, pass recipients as command-line arguments).

In -t mode, recipient addresses are appended to the sendmail command line without a -- end-of-options separator. A recipient address beginning with - (which Symfony\Component\Mime\Address accepts as valid) is therefore interpreted by sendmail as a command-line option rather than an address.

Resolution

The SendmailTransport transport now ensure -- is set before the list of recipients.

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Risk Scores
Base Score
6.2

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
6.2

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.41%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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