CVE-2023-46136 is a high-severity (CVSS 8) Uncontrolled Resource Consumption vulnerability in werkzeug. A fix is available for werkzeug — see the affected versions and patch details below.
Werkzeug vulnerable to high resource usage when parsing multipart/form-data containing a large part with CR/LF character at the beginning
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-46136 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
werkzeug🐍werkzeugReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Werkzeug is a comprehensive WSGI web application library. In versions on the 3.x branch prior to 3.0.1 and on the 2.x branch prior to 2.3.8, if an upload of a file that starts with CR or LF and then is followed by megabytes of data without these characters: all of these bytes are appended chunk by chunk into internal bytearray and lookup for boundary is performed on growing buffer. This allows an attacker to cause a denial of service by sending crafted multipart data to an endpoint that will parse it. The amount of CPU time required can block worker processes from handling legitimate requests. This vulnerability has been patched in version 3.0.1 and 2.3.8.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | werkzeug | ≥ 3.0.0&&< 3.0.1 | 3.0.1pip install --upgrade 'werkzeug==3.0.1' |
| 🐍PyPI | werkzeug | ≥ 2.0.0rc1&&< 2.3.8 | 2.3.8pip install --upgrade 'werkzeug==2.3.8' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for werkzeug, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update werkzeug to 3.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46136 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-46136 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-46136. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
The vulnerability found in python-werkzeug, which lets attackers carry out denial of service attacks by using carefully crafted multipart data, is considered a moderate issue because it could affect system resources and availability. When this vulnerability is exploited, it can cause the CPU to work excessively hard…
| Product | Fixed in | Advisory |
|---|---|---|
| Ironic content for Red Hat OpenShift Container Platform 4.12 | python-werkzeug-0:2.0.3-5.el9 | RHSA-2023:7610 |
| Ironic content for Red Hat OpenShift Container Platform 4.13 | python-werkzeug-0:2.0.3-5.el9 | RHSA-2023:7477 |
| Red Hat Ceph Storage 8.1 | oath-toolkit-0:2.6.12-1.el9cp | RHSA-2025:9775 |
| Red Hat OpenShift Container Platform 4.14 | python-werkzeug-0:2.2.3-2.el9 | RHSA-2023:7473 |
| Red Hat OpenStack Platform 17.1 for RHEL 8 | python-werkzeug-0:2.0.1-8.el8ost | RHSA-2024:0189 |
| Red Hat OpenStack Platform 17.1 for RHEL 9 | python-werkzeug-0:2.0.1-6.el9ost | RHSA-2024:0214 |
Frequently Asked Questions
Is CVE-2023-46136 in your dependencies?
O3 Security finds CVE-2023-46136 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.