GHSA-pp6c-gr5w-3c5g — python-multipart
HIGHGHSA-pp6c-gr5w-3c5g is a high-severity (CVSS 7.5) CWE-770 vulnerability in python-multipart. A fix is available for python-multipart — see the affected versions and patch details below.
python-multipart has Denial of Service via unbounded multipart part headers
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-pp6c-gr5w-3c5g.
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
GHSA-pp6c-gr5w-3c5g 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 377,636 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
python-multipartReal-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
Summary
python-multipart has a denial of service vulnerability in multipart part header parsing. When parsing multipart/form-data, MultipartParser previously had no limit on the number of part headers or the size of an individual part header. An attacker could send a request with either many repeated headers without terminating the header block or a single very large header value, causing excessive CPU work before request rejection or completion.
Impact
Applications that parse attacker-controlled multipart/form-data with affected versions of python-multipart can experience CPU exhaustion. ASGI applications using Starlette, FastAPI, or other frameworks that invoke python-multipart may have worker or event-loop delays while processing malicious upload requests.
Details
The affected parser states are HEADER_FIELD_START, HEADER_FIELD, HEADER_VALUE_START, HEADER_VALUE, and HEADER_VALUE_ALMOST_DONE. The issue can be triggered by:
- A multipart part with an oversized individual header value.
- A multipart part with many repeated header lines or an unterminated header block.
Both variants are addressed by enforcing default parser limits for maximum header count and maximum header size.
Mitigation
Upgrade to python-multipart 0.0.27 or later.
If upgrading is not immediately possible, reduce exposure by enforcing request body size limits at the server, proxy, or framework layer. This is only a mitigation; affected versions of python-multipart still parse multipart part headers without the default header count and header size limits.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | python-multipart | all versions | 0.0.27pip install --upgrade 'python-multipart==0.0.27' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for python-multipart, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update python-multipart to 0.0.27 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pp6c-gr5w-3c5g 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 GHSA-pp6c-gr5w-3c5g can be triaged on real exposure rather than presence alone.
Tailored to GHSA-pp6c-gr5w-3c5g. 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.
This is an Important denial of service vulnerability in python-multipart. A remote attacker can trigger excessive CPU utilization by sending specially crafted multipart/form-data requests, leading to service disruption.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Ansible Automation Platform 2.6 | ansible-automation-platform-26/lightspeed-chatbot-rhel9:1783832856 | RHSA-2026:42132 |
| Red Hat Ansible Automation Platform 2.7 | ansible-automation-platform-27/lightspeed-chatbot-rhel9:1783923914 | RHSA-2026:42142 |
| Red Hat Migration Toolkit for Applications 8.2 | mta/mta-solution-server-rhel9:1784109883 | RHSA-2026:43038 |
| Red Hat OpenShift AI 3.3 | rhoai/odh-mlserver-rhel9:1782887848 | RHSA-2026:37275 |
| Red Hat Satellite 6.17 | satellite/iop-advisor-engine-rhel9:1784834402 | RHSA-2026:44696 |
| Red Hat Satellite 6.18 | satellite/iop-vulnerability-engine-rhel9:1784554123 | RHSA-2026:51357 |
| Red Hat Satellite 6.19 | satellite/iop-vmaas-rhel9:1785929994 | RHSA-2026:51194 |
| Red Hat Satellite 6.19 | satellite/iop-vulnerability-engine-rhel9:1785806554 | RHSA-2026:51219 |
Frequently Asked Questions
Is GHSA-pp6c-gr5w-3c5g in your dependencies?
O3 Security finds GHSA-pp6c-gr5w-3c5g across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.