The vulnerability is found in django.core.mail.backends.smtp.EmailBackend, which allows a partially‑initialized SMTP connection to be reused after a failed STARTTLS handshake when fail_silently=True. This means an on‑path attacker can read email content in cleartext, violating confidentiality. The weakness is a cleartext transmission of sensitive information (CWE‑319) and occurs because the system does not enforce encryption after a failed TLS negotiation (CWE‑325).

Django 6.0 versions earlier than 6.0.6 and Django 5.2 versions earlier than 5.2.15 may be affected. Earlier Django series such as 5.0.x, 4.1.x, and 3.2.x were not evaluated but could also potentially be vulnerable.

The CVSS score of 2.3 indicates a low severity impact. EPSS is not available and the vulnerability is not listed in the CISA KEV catalog. An attacker would need on‑path network access and the ability to observe or influence a failed STARTTLS handshake; the exploit would allow eavesdropping but does not provide code execution or broader system compromise. The overall risk is moderate for confidentiality but low for overall system compromise.