Which products and versions are affected by CVE-2020-26258?

Affected: Struts (Apache); Xstream versions >= < 1.4.15; Debian Linux versions 10.0, 9.0, among others. The full list is in the CVE brief.

Is CVE-2020-26258 being exploited in the wild?

It is not listed in any known-exploited vulnerabilities catalog.

Is CVE-2020-26258 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2020-26258?

No public exploit code is known.

How urgently should CVE-2020-26258 be patched?

Brandefense priority: patch immediately, because it is very likely to be exploited soon.

Request A Demo

Vulnerability Intelligence

CVE-2020-26258

Q: What is CVE-2020-26258?

XStream is a Java library to serialize objects to XML and back again.

Q: Is CVE-2020-26258 being exploited in the wild?

It is not listed in any known-exploited vulnerabilities catalog.

Q: Is CVE-2020-26258 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Q: Is there a public exploit for CVE-2020-26258?

No public exploit code is known.

Q: Is there a fix for CVE-2020-26258?

Fixed versions are available, including Struts 6.0.0, cobbler 3.0.0+git20190806.32c4bae0-5.6.4, com.thoughtworks.xstream:xstream 1.4.15.

Q: How urgently should CVE-2020-26258 be patched?

Brandefense priority: patch immediately, because it is very likely to be exploited soon.

High

Server-Side Forgery Request can be activated unmarshalling with XStream

Published Dec 21, 2020 · Updated Oct 9, 2026 · Also known as DEBIAN-CVE-2020-26258, DLA-2507-1, DSA-4828-1, GHSA-4cch-wxpw-8p28, UBUNTU-CVE-2020-26258

Key Facts

Patch immediately

CVE-2020-26258 is a high-severity vulnerability (CVSS 7.7 v3.1) affecting Struts (Apache), Xstream, Debian Linux and 22 more products.
It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
EPSS estimates a 82% probability of exploitation in the next 30 days.
Fixed versions are available, including Struts 6.0.0, cobbler 3.0.0+git20190806.32c4bae0-5.6.4, com.thoughtworks.xstream:xstream 1.4.15.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.

CVSS v3.1

7.7

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

EPSS (30-day exploit likelihood)

82%

Higher than 99.6% of all scored CVEs

Exploited in the wild

No known

Not in a known-exploited catalog

Public exploit code

None known

Get the full CVE-2020-26258 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.15, a Server-Side Forgery Request vulnerability can be activated when unmarshalling. The vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.15. The reported vulnerability does not exist if running Java 15 or higher. No user is affected who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability. Users of XStream 1.4.14 or below who still want to use XStream default blacklist can use a workaround described in more detailed in the referenced advisories.

Affected Products

140 affected entries in total

Product	Affected versions	Fixed in
StrutsApache	See advisory	6.0.0
XstreamXstream	>= < 1.4.15	1.4.15
Debian LinuxDebian	10.0, 9.0	n/a
FedoraFedoraproject	33, 34, 35	n/a
libxstream-javadebian	See advisory	1.4.15-1

20 more affected products in the full CVE brief

Patched Releases

Struts

6.0.0

cobbler

3.0.0+git20190806.32c4bae0-5.6.4

com.thoughtworks.xstream:xstream

1.4.15

grafana-formula

0.4.0-3.6.2

libxstream-java

1.4.11.1-1+deb10u2, 1.4.11.1-1+deb9u1, 1.4.11.1-1~18.04.1, 1.4.11.1-1~18.04.2, 1.4.11.1-1ubuntu0.1, 1.4.11.1-1ubuntu0.2, 1.4.15-1, 1.4.7-1ubuntu0.1+esm2, 1.4.8-1ubuntu0.1+esm3

mgr-libmod

4.1.7-3.16.2

mgr-osa-dispatcher

4.1.5-2.9.4

mgr-osad

4.1.5-2.9.4

prometheus-exporters-formula

0.9.0-3.19.2

prometheus-formula

0.3.1-3.6.2

py26-compat-salt

2016.11.10-6.11.2

python3-mgr-osa-common

4.1.5-2.9.4

python3-mgr-osa-dispatcher

4.1.5-2.9.4

python3-mgr-osad

4.1.5-2.9.4

python3-rhnlib

4.1.3-4.3.2

python3-spacewalk-check

4.1.9-4.12.4

python3-spacewalk-client-setup

4.1.9-4.12.4

python3-spacewalk-client-tools

4.1.9-4.12.4

rhnlib

4.1.3-4.3.2

smdba

1.7.8-0.3.6.2

spacewalk-backend

4.1.21-4.22.7

spacewalk-backend-app

4.1.21-4.22.7

spacewalk-backend-applet

4.1.21-4.22.7

spacewalk-backend-config-files

4.1.21-4.22.7

spacewalk-backend-config-files-common

4.1.21-4.22.7

Timeline

Publicly disclosed
Dec 21, 2020
Last updated
Oct 9, 2026

Weakness Type

CWE-918 Server-Side Request Forgery (SSRF)

References

15 more references in the full CVE brief

FAQ

Common Questions.

XStream is a Java library to serialize objects to XML and back again.
Affected: Struts (Apache); Xstream versions >= < 1.4.15; Debian Linux versions 10.0, 9.0, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Struts 6.0.0, cobbler 3.0.0+git20190806.32c4bae0-5.6.4, com.thoughtworks.xstream:xstream 1.4.15.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.

Is CVE-2020-26258 Running On Your Attack Surface?

Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.

Request A Demo