GHSA-78cv-mqj4-43f7 is a medium-severity (CVSS 5.4) CWE-159 vulnerability in tornado. A fix is available for tornado — see the affected versions and patch details below.
Tornado has incomplete validation of cookie attributes
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-78cv-mqj4-43f7.
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-78cv-mqj4-43f7 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
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
Values passed to the domain, path, and samesite arguments of RequestHandler.set_cookie were not completely validated in versions of Tornado prior to 6.5.5. In particular, semicolons would be allowed, which could be used to inject attacker-controlled values for other cookie attributes.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | tornado | all versions | 6.5.5pip install --upgrade 'tornado==6.5.5' |
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 6.5.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-78cv-mqj4-43f7 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-78cv-mqj4-43f7 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-78cv-mqj4-43f7. 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.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | python-tornado-0:6.5.5-1.el10_1.1 | RHSA-2026:13641 |
| Red Hat Enterprise Linux 10 | python-tornado-0:6.5.5-1.el10_2 | RHSA-2026:19034 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | python-tornado-0:6.4.2-1.el10_0.2 | RHSA-2026:20577 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | python-tornado-0:4.2.1-5.el7_9.3 | RHSA-2026:24342 |
| Red Hat Enterprise Linux 9 | python-tornado-0:6.5.5-1.el9_7.1 | RHSA-2026:13670 |
| Red Hat Enterprise Linux 9 | python-tornado-0:6.5.5-1.el9_8 | RHSA-2026:19189 |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | python-tornado-0:6.4.2-1.el9_2.2 | RHSA-2026:20573 |
| Red Hat Enterprise Linux 9.4 Extended Update Support | python-tornado-0:6.4.2-1.el9_4.2 | RHSA-2026:20810 |
Frequently Asked Questions
Is GHSA-78cv-mqj4-43f7 in your dependencies?
O3 Security finds GHSA-78cv-mqj4-43f7 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.