GHSA-vf6r-mmhc-3xcm — undertow-core
MEDIUMGHSA-vf6r-mmhc-3xcm is a medium-severity (CVSS 5.3) Information Exposure vulnerability in io.undertow:undertow-core. A fix is available for io.undertow:undertow-core — see the affected versions and patch details below.
Exposure of Sensitive Information to an Unauthorized Actor in Undertow
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-vf6r-mmhc-3xcm 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 379,842 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
io.undertow:undertow-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
An information leak vulnerability was found in Undertow. If all headers are not written out in the first write() call then the code that handles flushing the buffer will always write out the full contents of the writevBuffer buffer, which may contain data from previous requests.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.undertow:undertow-core | all versions | 2.0.19.FINALio.undertow:undertow-core:2.0.19.FINAL |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.undertow:undertow-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.undertow:undertow-core to 2.0.19.FINAL or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vf6r-mmhc-3xcm 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-vf6r-mmhc-3xcm can be triaged on real exposure rather than presence alone.
Tailored to GHSA-vf6r-mmhc-3xcm. 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 JBoss EAP 7.2 | undertow | RHSA-2019:1106 |
| Red Hat JBoss Enterprise Application Platform 7.1 for RHEL 6 | eap7-activemq-artemis-0:1.5.5.015-1.redhat_00001.1.ep7.el6 | RHSA-2019:0364 |
| Red Hat JBoss Enterprise Application Platform 7.1 for RHEL 7 | eap7-activemq-artemis-0:1.5.5.015-1.redhat_00001.1.ep7.el7 | RHSA-2019:0365 |
| Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 6 | eap7-activemq-artemis-0:2.6.3-5.redhat_00020.1.el6eap | RHSA-2019:1107 |
| Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 7 | eap7-activemq-artemis-0:2.6.3-5.redhat_00020.1.el7eap | RHSA-2019:1108 |
| Red Hat Single Sign-On 7.2.6 zip | undertow | RHSA-2019:0380 |
| Red Hat Single Sign-On 7.3.1 zip | see advisory | RHSA-2019:1140 |
| Red Hat Virtualization 4 for Red Hat Enterprise Linux 7 | rhvm-appliance-0:4.3-20190502.0.el7 | RHEA-2019:1119 |
Frequently Asked Questions
Is GHSA-vf6r-mmhc-3xcm in your dependencies?
O3 Security finds GHSA-vf6r-mmhc-3xcm across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.