CyberSecBulletin
CVE-2021-39144Exploited in the wildNVD status: Analyzed

XStream Remote Code Execution

Published Updated By the CyberSecBulletin desk

CVE-2021-39144 is a high-severity missing authentication for critical functionality vulnerability in xstream from X-stream, with a CVSS 3.1 base score of 8.5 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected xstream versions: < 1.4.18. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on March 10, 2023, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Check which version of xstream you run against the affected versions below, and install the vendor's latest release.
  2. CISA's required action: Apply updates per vendor instructions.
  3. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
X-streamxstream< 1.4.18Not stated
DebianDebian Linux9.0; 10.0; 11.0Not stated
Fedora ProjectFedora33; 34; 35Not stated
NetAppSnapmanagerNot specified in the recordNot stated
OracleBusiness Activity Monitoring12.2.1.4.0Not stated
OracleCommerce Guided Search11.3.2Not stated
OracleCommunications Billing And Revenue Management Elastic Charging Engine11.3; 12.0Not stated
OracleCommunications Cloud Native Core Automated Test Suite1.9.0Not stated
OracleCommunications Cloud Native Core Binding Support Function1.10.0Not stated
OracleCommunications Cloud Native Core Policy1.14.0Not stated
OracleCommunications Unified Inventory Management7.3.4; 7.3.5; 7.4.0; 7.4.1; 7.4.2Not stated
OracleRetail Xstore Point Of Service16.0.6; 17.0.4; 18.0.3; 19.0.2; 20.0.1Not stated
OracleUtilities Framework4.2.0.2.0; 4.2.0.3.0; 4.3.0.1.0; 4.3.0.6.0; 4.4.0.0.0; 4.4.0.2.0; 4.4.0.3.0Not stated
OracleUtilities Testing Accelerator6.0.0.1.1Not stated
OracleWebcenter Portal12.2.1.3.0; 12.2.1.4.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.5HighCNA (github.com)
CVSS 3.18.5HighNVD
CVSS 2.06.0MediumNVD

Official description

XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the host 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. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Missing Authentication for Critical Functionality

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

How developers prevent this class of flaw

  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
  • When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.

More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Technical write-ups (may include proof of concept)

Other vulnerabilities in xstream

All xstream vulnerabilities

Recent Missing Authentication for Critical Functionality vulnerabilities

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