CVE-2020-26259

What it is

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.15, is vulnerable to an Arbitrary File Deletion on the local host when unmarshalling. The vulnerability may allow a remote attacker to delete arbitrary know files on the host as log as the executing process has sufficient rights 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 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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data tampering.

Exploit odds

82.4% chance of exploitation in the next 30 days (EPSS). Higher than most.

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-10-01 00:00 UTC ReservedThe CVE id was reserved by its CNA
2. 2020-12-16 01:15 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-10-07 19:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 82.4% in the next 30 days (EPSS).
• Severity: 6.8 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-12-16 01:15 UTC

Last modified

2026-10-07 19:17 UTC

Exploit probability

82.4% · EPSS, next 30 days

Weakness

CWE-78 · OS command injection

Record status

Analyzed

Affected

• Apache Struts < 6.0.0
• Xstream < 1.4.15
• Debian Linux 9.0
• Debian Linux 10.0
• Fedoraproject Fedora 33
• Fedoraproject Fedora 34
• Fedoraproject Fedora 35

Attack profile CVSS 3.1 · 6.8

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-26259.md and follow it. Check whether this project is affected by CVE-2020-26259. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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