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Fencer Vulns
medium 6.1

CVE-2021-20293 json

Cross-Site Scripting

published 2021-06-10 5 y ago modified 2026-06-17 4 mo ago also GHSA-5h26-c766-g93v , EUVD-2021-1269

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 58%
public exploits
0
none known

Summary

A reflected Cross-Site Scripting (XSS) flaw was found in RESTEasy in all versions of RESTEasy up to 4.6.0.Final, where it did not properly handle URL encoding when calling @javax.ws.rs.PathParam without any @Produces MediaType. This flaw allows an attacker to launch a reflected XSS attack. The highest threat from this vulnerability is to data confidentiality and integrity.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-20293 updated cvss 5.4

RESTEasy: PathParam in RESTEasy can lead to a reflected XSS attack

  • Red Hat build of Quarkus resteasy Red Hat Enterprise Linux 7 resteasy-base, resteasy-base-tjws, resteasy-base-jaxrs, resteasy-base-client, resteasy-base-javadoc, resteasy-base-jaxrs-all, +7 more Red Hat Enterprise Linux 8 resteasy, resteasy-javadoc Red Hat Fuse 7 resteasy Red Hat Integration Camel K 1 resteasy-core Red Hat Integration Camel Quarkus 1 resteasy-core
    affected: no fix planned “Will not fix”
  • Red Hat JBoss Enterprise Application Platform 6 resteasy
    affected: no fix planned “Out of support scope”
  • Red Hat JBoss Enterprise Application Platform 7 resteasy Red Hat JBoss Enterprise Application Platform Expansion Pack resteasy
    affected: no fix planned “Will not fix”
  • Red Hat OpenShift Application Runtimes resteasy
    affected: no fix planned “Out of support scope”
  • Red Hat Satellite 6 resteasy Red Hat Single Sign-On 7 resteasy Red Hat support for Spring Boot resteasy
    affected: no fix planned “Will not fix”
  • Red Hat RHINT Camel-K 1.6.4
    fixed: vendor fix RHSA-2022:1029
  • Red Hat RHINT Service Registry 2.0.2 GA
    fixed: vendor fix RHSA-2021:4100

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.86% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.jboss.resteasy:resteasy-bom
<=4.6.0.Final
 no fix listed
maven org.jboss.resteasy:resteasy-core
<=4.6.0.Final
 no fix listed

Affected products

  • n/a RESTEasy

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.