How severe is CVE-2018-12541?

CVE-2018-12541 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2018-12541?

CVE-2018-12541 affects the following packages: io.vertx:vertx-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2018-12541?

Update io.vertx:vertx-core to 3.5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-12541 is resolved across your whole dependency graph.

How do I detect CVE-2018-12541 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.vertx:vertx-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2018-12541 if there is no patch (or I can't update yet)?

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.

Is CVE-2018-12541 actively exploited in the wild?

No public exploit code has been indexed for CVE-2018-12541 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2018-12541?

CVE-2018-12541 has an EPSS (Exploit Prediction Scoring System) score of 2.7%, placing it in the 86th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2018-12541?

CVE-2018-12541 is classified as CWE-789 (CWE-789), Buffer Overflow (CWE-119). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2018-12541 published, and has it been updated?

CVE-2018-12541 was published on October 10, 2018 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2018-12541 — vertx-core

MEDIUMFix: eclipse-vertx/vert.x@269a583

CVE-2018-12541 is a medium-severity (CVSS 6.5) CWE-789 vulnerability in io.vertx:vertx-core. A fix is available for io.vertx:vertx-core — see the affected versions and patch details below.

Excessive memory allocation

Also known asGHSA-45xm-v8gq-7jqx

Published

Oct 10, 2018

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs86th percentile — riskier than 86% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕io.vertx:vertx-core

Real-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

In version from 3.0.0 to 3.5.3 of Eclipse Vert.x, the WebSocket HTTP upgrade implementation buffers the full http request before doing the handshake, holding the entire request body in memory. There should be a reasonnable limit (8192 bytes) above which the WebSocket gets an HTTP response with the 413 status code and the connection gets closed.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.vertx:vertx-core`	≥ 3.0.0&&< 3.5.4	3.5.4`io.vertx:vertx-core:3.5.4`

Affected Products

1 product · 1 configurations

Application

vert.xeclipse

≥ 3.0.0 && < 3.5.4

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.vertx:vertx-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.vertx:vertx-core to 3.5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-12541 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.

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.

Red HatModerate

Product	Fixed in	Advisory
Red Hat Fuse 7.7.0	`vertx-core`	RHSA-2020:3192
Text-Only RHOAR	`vert-core`	RHSA-2018:2946

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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