CVE-2025-47287 is a high-severity (CVSS 7.5) CWE-770 vulnerability in tornado. A fix is available for tornado — see the affected versions and patch details below.
Tornado vulnerable to excessive logging caused by malformed multipart form data
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 CVE-2025-47287.
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-2025-47287 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 379,145 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
tornadoReal-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
Tornado is a Python web framework and asynchronous networking library. When Tornado's multipart/form-data parser encounters certain errors, it logs a warning but continues trying to parse the remainder of the data. This allows remote attackers to generate an extremely high volume of logs, constituting a DoS attack. This DoS is compounded by the fact that the logging subsystem is synchronous. All versions of Tornado prior to 6.5.0 are affected. The vulnerable parser is enabled by default. Upgrade to Tornado version 6.50 to receive a patch. As a workaround, risk can be mitigated by blocking Content-Type: multipart/form-data in a proxy.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | tornado | all versions | 6.5pip install --upgrade 'tornado==6.5' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tornado, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tornado to 6.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-47287 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-2025-47287 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-47287. 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 vulnerability marked as Important because it leverages the synchronous nature of the logging subsystem to induce a DoS condition. Specifically, malformed multipart/form-data payloads cause repeated, blocking log writes, which stall the event loop that underpins Tornado’s asynchronous architecture. Furthermore,…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | python-tornado-0:6.4.2-1.el10_0.1 | RHSA-2025:8135 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | python-tornado-0:4.2.1-5.el7_9.1 | RHSA-2025:8664 |
| Red Hat Enterprise Linux 8 | pcs-0:0.10.18-2.el8_10.5 | RHSA-2025:8254 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | pcs-0:0.10.8-1.el8_4.7 | RHSA-2025:8323 |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | pcs-0:0.10.12-6.el8_6.8 | RHSA-2025:8290 |
| Red Hat Enterprise Linux 8.8 Extended Update Support | pcs-0:0.10.15-4.el8_8.6 | RHSA-2025:8279 |
| Red Hat Enterprise Linux 9 | python-tornado-0:6.4.2-2.el9_6.2 | RHSA-2025:8136 |
| Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | pcs-0:0.11.1-10.el9_0.8 | RHSA-2025:8291 |
Frequently Asked Questions
Is CVE-2025-47287 in your dependencies?
O3 Security finds CVE-2025-47287 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.