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

> On-path attackers can read email content in cleartext if Django's SMTP backend reuses a failed STARTTLS connection with fail_silently enabled.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 3 Jun 2026
- **Updated:** 3 Jun 2026
- **Also known as:** BIT-django-2026-7666, DEBIAN-CVE-2026-7666, ECHO-45a8-c123-8d52, GHSA-mm6v-q8q9-pgcf, MINI-j4g8-q4fh-c38c, PYSEC-2026-200, UBUNTU-CVE-2026-7666

## What is CVE-2026-7666?

CVE-2026-7666 is a low-severity vulnerability in Djangoproject Django, published on 3 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-319 (Cleartext Transmission of Sensitive Information)

## Which versions are affected by CVE-2026-7666?

6 open source packages ship an affected version, including django. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `django` | Bitnami | From 5.2.0 | 5.2.15, 6.0.6 |
| `django` | PyPI | From 5.2 | 5.2.15, 6.0.6 |
| `django` | PyPI | From 5.2 | 5.2.15 |
| `django` | PyPI | From 5.2 | 5.2.15 |
| `django` | PyPI | From 6.0 | 6.0.6 |
| `django` | PyPI | From 6.0 | 6.0.6 |

Products: Djangoproject Django.

## How do I fix CVE-2026-7666?

Upgrade django to a fixed version for your release line: 5.2.15 or 6.0.6.

## Is CVE-2026-7666 being exploited?

There is no known exploitation of CVE-2026-7666 in the wild and no public exploit code.

## Other vulnerabilities in Djangoproject Django

- [CVE-2026-4277](https://insights.sbomify.com/CVE-2026-4277/): Privilege abuse in GenericInlineModelAdmin (critical 9.8)
- [CVE-2024-53908](https://insights.sbomify.com/CVE-2024-53908/): Django SQL injection in HasKey(lhs, rhs) on Oracle (critical 9.8)
- [CVE-2024-42005](https://insights.sbomify.com/CVE-2024-42005/): Django SQL injection vulnerability (critical 9.8)
- [CVE-2023-31047](https://insights.sbomify.com/CVE-2023-31047/): Django bypasses validation when using one form field to upload multiple files (critical 9.8)
- [CVE-2022-34265](https://insights.sbomify.com/CVE-2022-34265/): Django `Trunc()` and `Extract()` database functions vulnerable to SQL Injection (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-7666 and fix it if it is affected.

What it is: CVE-2026-7666 is a low-severity vulnerability in Djangoproject Django, published on 3 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-7666 in the wild and no public exploit code.

Affected packages and fixed versions:
- django (Bitnami): affected from 5.2.0; fixed in 5.2.15, 6.0.6
- django (PyPI): affected from 5.2; fixed in 5.2.15, 6.0.6
- django (PyPI): affected from 5.2; fixed in 5.2.15
- django (PyPI): affected from 5.2; fixed in 5.2.15
- django (PyPI): affected from 6.0; fixed in 6.0.6
- django (PyPI): affected from 6.0; fixed in 6.0.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-7666/ (Markdown: https://insights.sbomify.com/CVE-2026-7666/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-7666
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-7666
- OSV: https://osv.dev/vulnerability/CVE-2026-7666

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-7666/
Summaries are generated and may contain mistakes; the official description above is the record.