How severe is CVE-2020-10687?

CVE-2020-10687 has a CVSS score of 4.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-10687?

CVE-2020-10687 affects the following packages: io.undertow:undertow-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2020-10687?

Update io.undertow:undertow-core to 2.2.0.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-10687 is resolved across your whole dependency graph.

How do I detect CVE-2020-10687 in my Maven dependencies?

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.

How do I mitigate CVE-2020-10687 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2020-10687 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-10687 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-2020-10687?

CVE-2020-10687 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 68th 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-2020-10687?

CVE-2020-10687 is classified as CWE-444 (CWE-444). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-10687 published, and has it been updated?

CVE-2020-10687 was published on September 23, 2020 and was last updated on July 8, 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-2020-10687 — undertow-core

MEDIUM

CVE-2020-10687 is a medium-severity (CVSS 4.8) CWE-444 vulnerability in io.undertow:undertow-core. A fix is available for io.undertow:undertow-core — see the affected versions and patch details below.

HTTP Request Smuggling in Undertow

Also known asGHSA-p9w3-gwc2-cr49

Published

Sep 23, 2020

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2020-10687 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

☕io.undertow:undertow-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

A flaw was discovered in all versions of Undertow before Undertow 2.2.0.Final, where HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.undertow:undertow-core`	all versions	2.2.0.Final`io.undertow:undertow-core:2.2.0.Final`

Affected Products

3 products · 7 configurations

Application

jboss enterprise application platformredhat

3 versions

7.27.37.4

Application

single sign-onredhat

all

Application

undertowredhat

< 2.2.0

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.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 2.2.0.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-10687 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

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	see advisory	RHSA-2020:3192
Red Hat JBoss Enterprise Application Platform 7	`wildfly-undertow`	RHSA-2020:3642
Red Hat JBoss Enterprise Application Platform 7	see advisory	RHSA-2021:0885
Red Hat JBoss Enterprise Application Platform 7	`wildfly-undertow`	RHSA-2020:3464
Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 6	`eap7-dom4j-0:2.1.3-1.redhat_00001.1.el6eap`	RHSA-2020:3637
Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 7	`eap7-dom4j-0:2.1.3-1.redhat_00001.1.el7eap`	RHSA-2020:3638
Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 8	`eap7-dom4j-0:2.1.3-1.redhat_00001.1.el8eap`	RHSA-2020:3639
Red Hat JBoss Enterprise Application Platform 7.3 for RHEL 6	`eap7-dom4j-0:2.1.3-1.redhat_00001.1.el6eap`	RHSA-2020:3461

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-10687 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

4.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CWE Classification

CWE-444CWE-444

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Sep 23, 2020

Last updated

Jul 8, 2026

Identifiers

CVE-2020-10687

GHSA-p9w3-gwc2-cr49

References

Advisorysecurity.netapp.com Advisorynvd.nist.gov Reportbugzilla.redhat.com Weblists.apache.org Weblists.apache.org Websecurity.netapp.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting undertow-core are rated as high or higher (top: critical).

CVE-2026-3260CVE-2024-4027CVE-2025-12543CVE-2024-3884CVE-2025-9784CVE-2023-4639CVE-2023-1973CVE-2024-7885

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJul 8, 2026

CVE-2020-10687 — undertow-core

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2020-10687 in your dependencies?