Django fails to prevent reuse of a partially-initialized connection after a failed `STARTTLS` handshake

CVE-2026-7666 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

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.

Basic information

Type
reviewed
Severity
low
Advisory on GitHub
Open advisory ↗
Repository advisory
—
Source code
Browse source ↗
Published (advisory)
2026-06-03 15:30:43 UTC
Updated
2026-07-13 17:26:40 UTC
GitHub reviewed
2026-07-13 17:26:39 UTC
NVD published
2026-06-03

EPSS Score

Score Percentile
0.15% 4.58%

CVSS Scores

Base score Version Severity Vector
3.1 3.1 —
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
2.3 4.0 —
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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:H)
Exploitation depends on constrained or hard-to-reproduce conditions.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:P)
A user has to participate (for example click/open/approve).
Vulnerable system confidentiality impact (VC:L)
Limited confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.

Identifiers

Type Value
GHSA GHSA-mm6v-q8q9-pgcf ↗
CVE CVE-2026-7666 ↗

CWEs

CWE id Name
CWE-319 Cleartext Transmission of Sensitive Information

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip django >= 5.2, < 5.2.15 5.2.15 —
pip django >= 6.0, < 6.0.6 6.0.6 —

References

cvelogic Threat Intelligence