What’s Vulnerable › Vulnerabilities

CVE-2026-7666: Potential unencrypted email transmission via STARTTLS in the SMTP backend

• Severity: low (CVSS 3.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-03 · updated 2026-07-21
• Weakness: CWE-319

Description

An issue was discovered in Django 6.0 before 6.0.6 and 5.2 before 5.2.15. `django.core.mail.backends.smtp.EmailBackend` in Django fails to prevent reuse of a partially-initialized connection after a failed `STARTTLS` handshake when `fail_silently=True`, which allows on-path network attackers to read email content via cleartext interception. Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Kasper Dupont for reporting this issue.

Affected products

• Django: from 5.2 before 5.2.15; from 6.0 before 6.0.6 — fixed in 5.2.15, 6.0.6

How to fix

Upgrade to a fixed version: Django 5.2.15, 6.0.6. Check the vendor advisory for mitigations.

References

• https://docs.djangoproject.com/en/dev/releases/security/
• https://groups.google.com/g/django-announce
• https://www.djangoproject.com/weblog/2026/jun/03/security-releases/

Get alerted when CVE-2026-7666 or the next vulnerability affects your stack