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Case File

CVE-2020-26258

MEDIUM · CVSS 6.3 EPSS 81.82% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2020-12-16 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 6.3. It affects Java. Public exploit code or proof-of-concept references have been detected in its references. Its EPSS score suggests a 81.8% probability of exploitation in the next 30 days. It may be remotely exploitable.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2020-26258
Severity
MEDIUM
CVSS
6.3
EPSS
81.82%
Java

Original NVD 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.

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