Bug 2558553 (CVE-2026-114138)

Summary: CVE-2026-114138 djangorestframework: djangorestframework: Denial of Service via unbounded Accept header parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anthomas, brasmith, cmyers, cochase, dnakabaa, dranck, dschmidt, ehelms, ggainey, jlanda, jmitchel, jpasqual, juwatts, jwong, kaycoth, kshier, lbrazdil, lcouzens, mdellweg, mhulan, mminar, nmoumoul, omaciel, osousa, pcreech, rbiba, rbobbitt, rchan, simaishi, smallamp, sskracic, stcannon, tmalecek, tpfromme, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in djangorestframework. An unauthenticated remote attacker can cause a Denial of Service (DoS) by sending HTTP requests with a specially crafted Accept header containing an excessive number of media types with complex parameters. Because the framework performs unbounded and repetitive parsing of these header tokens across available renderers, processing such requests consumes disproportionate CPU resources. This can exhaust application worker processes and render the API service unavailable to legitimate users.
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Description OSIDB Bzimport 2026-10-21 20:31:57 UTC 
Django REST framework is a toolkit for building Web APIs. Prior to 3.18.2, DefaultContentNegotiation.get_accept_list in rest_framework/negotiation.py accepts an unbounded number and aggregate size of Accept tokens, while select_renderer in that file repeatedly invokes _MediaType parsing from rest_framework/utils/mediatypes.py for each attacker-controlled token, every renderer, and forced 406 renegotiation. A remote unauthenticated client can send many distinct media types containing large quoted parameter values with numerous semicolons, causing Django's parameter parser and DRF's repeated parsing structure to consume disproportionate CPU. Requests to any reachable endpoint can pin synchronous workers for prolonged periods, and concurrent requests can make the service unavailable until the requests stop. This issue is fixed in version 3.18.2.