XStream can cause a Denial of Service

Description

Impact

The vulnerability may allow a remote attacker to allocate 100% CPU time on the target system depending on CPU type or parallel execution of such a payload resulting in a denial of service only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.

Patches

XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.

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-2021-39140.

Credits

The vulnerability was discovered and reported by Lai Han of nsfocus security team.

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
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2021-08-25 14:48:39 UTC
Updated
2023-01-27 05:02:19 UTC
GitHub reviewed
2021-08-23 18:22:01 UTC
NVD published
2021-08-23

EPSS Score

Score Percentile
0.14% 33.62%

CVSS Scores

Base score Version Severity Vector
6.5 3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

CWEs

CWE id Name
CWE-502 Deserialization of Untrusted Data
CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

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