vulnerability / NVI-00010570 / Revision 1
Django REST framework: Accept header with many large quoted parameters burns ~19s of CPU per request in content negotiation
GitHub lists this reviewed advisory for djangorestframework. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
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01 / Meaning
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7.5 high
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As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
djangorestframework
source listed< 3.18.2
### Summary DRF's content negotiation parses each Accept token several times per request and never limits the number of tokens or their total size. Each parse ends up in Django's parse_header_parameters, which takes quadratic time when a quoted parameter value is packed with semicolons. On my machine a single GET with a 780KB Accept header made of 96 such tokens kept one gunicorn worker busy for 18.87 seconds (Django 6.1, djangorestframework 3.18.0, gunicorn 26.0.0, Python 3.13, Docker on macOS). The header is syntactically valid, fits inside gunicorn's default header limits, and needs no authentication. Two concurrent requests, which is one per sync worker, made a default two worker deployment stop answering for my whole 40 second test window. It recovered half a second after I stopped sending. ### Details #### What happens get_accept_list() splits the Accept header on commas with no cap on token count or total size, at rest_framework/negotiation.py:96-97. For every token, select_renderer() calls media_type_matches() once per renderer, and each call builds fresh _MediaType objects for both sides, at rest_framework/negotiation.py:53-56 and rest_framework/utils/mediatypes.py:2
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04 / Limits
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05 / Provenance
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- GHSA-33wh-fxxf-88vv ↗
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- Revision 1 ·
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