Django 6.0/5.2 ASGI Content-Length Bypass, FILE_UPLOAD_MAX_MEMORY_SIZE
CVE-2026-5766 Published on May 5, 2026
Potential denial-of-service vulnerability in ASGI requests via file upload limit bypass
An issue was discovered in 6.0 before 6.0.5 and 5.2 before 5.2.14.
ASGI requests with a missing or understated `Content-Length` header can bypass the `FILE_UPLOAD_MAX_MEMORY_SIZE` limit, potentially loading large files into memory and causing service degradation.
As a reminder, Django expects a limit to be configured at the web server level rather than solely relying on `FILE_UPLOAD_MAX_MEMORY_SIZE`.
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 Kyle Agronick for reporting this issue.
Timeline
Initial report received.
Vulnerability confirmed. 695 days later.
Security release issued. 28 days later.
Weakness Type
What is a length manipulation Vulnerability?
The software parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data. If an attacker can manipulate the length parameter associated with an input such that it is inconsistent with the actual length of the input, this can be leveraged to cause the target application to behave in unexpected, and possibly, malicious ways. One of the possible motives for doing so is to pass in arbitrarily large input to the application. Another possible motivation is the modification of application state by including invalid data for subsequent properties of the application. Such weaknesses commonly lead to attacks such as buffer overflows and execution of arbitrary code.
CVE-2026-5766 has been classified to as a length manipulation vulnerability or weakness.
Products Associated with CVE-2026-5766
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Affected Versions
djangoproject Django:- Version 6.0 and below 6.0.5 is affected.
- Version 6.0.5 is unaffected.
- Version 5.2 and below 5.2.14 is affected.
- Version 5.2.14 is unaffected.