Vulnerability Monitor

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CVE-2020-26258


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.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.3, indicating it can be exploited remotely over the network but requires specific conditions to be met without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), for affected systems. Impacting 4 products from apache, from xstream, from debian and 1 other, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2020, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2020-12-16T01:15:12.333

Last Modified

2025-05-23T16:53:23.900

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 6.3 (MEDIUM)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:N/A:N

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: NONE
  • Availability Impact: NONE
Exploitability Score

10.0

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-918
  • Type: Primary
    CWE-918

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application apache struts < 6.0.0 Yes
Application xstream xstream < 1.4.15 Yes
Operating System debian debian_linux 9.0 Yes
Operating System debian debian_linux 10.0 Yes
Operating System fedoraproject fedora 33 Yes
Operating System fedoraproject fedora 34 Yes
Operating System fedoraproject fedora 35 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For apache's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.