A Server-Side Forgery Request can be activated unmarshalling with XStream to access data streams from an arbitrary URL referencing a resource in an intranet or the local host

CVE-2021-39150 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

Impact

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 with a Java runtime version 14 to 8. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.

Patches

If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.18.

Workarounds

See workarounds for the different versions covering all CVEs.

References

See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for CVE-2021-39150.

Credits

Lai Han of NSFOCUS security team found and reported the issue to XStream and provided the required information to reproduce it.

For more information

If you have any questions or comments about this advisory:
* Open an issue in XStream
* Contact us at XStream Google Group

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2021-08-25 14:47:19 UTC
Updated
2023-01-27 05:02:32 UTC
GitHub reviewed
2021-08-23 18:22:24 UTC
NVD published
2021-08-23

EPSS Score

Score Percentile
2.42% 84.96%

CVSS Scores

Base score Version Severity Vector
8.6 3.1 —
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

Type Value
GHSA GHSA-cxfm-5m4g-x7xp ↗
CVE CVE-2021-39150 ↗

CWEs

CWE id Name
CWE-502 Deserialization of Untrusted Data
CWE-918 Server-Side Request Forgery (SSRF)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
maven com.thoughtworks.xstream:xstream < 1.4.18 1.4.18 —

References

cvelogic Threat Intelligence