Cloudanix VulnDB

CVE-2026-114138

High · 7.5

CVSS

7.5

EPSS

0.6%

Published

Oct 21, 2026

CISA due date

—

Cloudanix analysis

Next patch cycle SSVC: Track

Attackers can send specially crafted web requests that overload an API service and make it stop responding to legitimate users.

Exploitation
Remote Unauthenticated
Attacker needs
None
Complexity
Low
Impact
Denial Of Service
Component
Web Framework
Class
Denial of service
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Unbounded Accept header tokens with large quoted parameters trigger repeated expensive _MediaType parsing in DefaultContentNegotiation and select_renderer, exhausting CPU on synchronous workers.

Why it matters to the business

Attackers can cause prolonged request processing that makes API endpoints unresponsive, leading to service outages and operational disruption until malicious traffic stops.

How an attack unfolds

An unauthenticated remote attacker crafts HTTP requests containing many distinct media types, each with oversized quoted parameter values separated by numerous semicolons, forcing the framework to perform quadratic parsing work across all configured renderers and 406 renegotiations on every reachable endpoint.

How to fix it

Upgrade Django REST framework to version 3.18.2 or later; in the interim, place strict limits on Accept header size and token count at the web server or WSGI layer.

How to confirm the fix worked

Confirm the installed package version is at least 3.18.2; re-test affected endpoints with the original large Accept header payload and verify that request processing time remains bounded.

Typical attack path

  1. Identify any publicly reachable DRF endpoint
  2. Construct a single request with hundreds of distinct Accept tokens containing large quoted strings and repeated semicolons
  3. Send the request (or many concurrent copies) to pin worker processes
  4. Repeat or sustain traffic until service becomes unavailable

How to detect it

Inspect web server or application logs for requests containing unusually large or complex Accept headers with many semicolons and quoted parameters; correlate with worker process CPU saturation or timeout events in negotiation.py paths.

  • Accept:.*;.*;.*;.*;.*;.*;.*;.*;.*;.*
  • rest_framework/negotiation.py
  • rest_framework/utils/mediatypes.py

What your security team should do

  • Immediately upgrade all Django REST framework installations to 3.18.2
  • Add WAF or proxy rules to cap Accept header size and token count
  • Monitor for sudden CPU spikes correlated with high-volume Accept headers
  • Review and reduce the number of configured renderers where possible

The record

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.

Affected packages

Ecosystem Package Introduced Fixed

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