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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2020-26259

In XStream before version 1.4.15, is vulnerable to an Arbitrary File Deletion on the local host when unmarshalling.

MEDIUM 6.8EPSS 82.4%

Does this matter?

EPSS puts the probability of exploitation in the next 30 days at 82.4%, higher than 100% of all known CVEs. Patch or mitigate before the next change window.

Description

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.

CVSS 3.1
6.8 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
EPSS
82.39% probability · 100th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-78
Affected
apache/struts · xstream/xstream · debian/debian linux · fedoraproject/fedora
Source
security-advisories@github.com
EPSS trend
0%43%85%26 October 2026: 82.39%26 October 202626 October 2026

EPSS 82.4% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.