# What is CVE-2021-39144?

> CVE-2021-39144 is a high-severity flaw (CVSS 8.5) in Xstream, published on 23 August 2021. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 98%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-39144

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 81 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 8.5 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 98% (latest exploit-likelihood forecast)
- **Published:** 23 August 2021
- **Record last updated:** 24 October 2025
- **Main product:** Xstream
- **Affected products:** 15

## What is CVE-2021-39144? In plain terms

It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The 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.

### What kind of flaw is it?

- CWE-94: Improper Control of Generation of Code ('Code Injection')
- CWE-502: Deserialization of Untrusted Data
- CWE-306: Missing Authentication for Critical Function

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Hard: conditions must line up
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

Severity vector: `CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H`

## Is CVE-2021-39144 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 98%.

Exploit likelihood over the last 7 days: 98%, 98%, 98%, 98%, 98%, 98%, 98%.

### Timeline

- 23 August 2021: Published
- 24 October 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2021-39144 scores **81 out of 100 (High)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2021-39144?

The published record lists 15 products. Versions are as published: "before 1.4.18" means every version up to, but not including, 1.4.18.

- [Xstream](https://www.precursorintelligence.com/product/xstream/xstream) by [Xstream](https://www.precursorintelligence.com/vendors/xstream) (Application): before 1.4.18
- [Utilities Framework](https://www.precursorintelligence.com/product/oracle/utilities_framework) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 4.2.0.2.0, 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, 4.4.0.3.0
- [Communications Unified Inventory Management](https://www.precursorintelligence.com/product/oracle/communications_unified_inventory_management) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 7.3.4, 7.3.5, 7.4.0, 7.4.1, 7.4.2
- [Retail Xstore Point of Service](https://www.precursorintelligence.com/product/oracle/retail_xstore_point_of_service) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 16.0.6, 17.0.4, 18.0.3, 19.0.2, 20.0.1
- [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 9.0, 10.0, 11.0
- [Fedora](https://www.precursorintelligence.com/product/fedoraproject/fedora) by [Fedoraproject](https://www.precursorintelligence.com/vendors/fedoraproject) (Operating system): 33, 34, 35
- [Communications Billing and Revenue Management Elastic Charging Engine](https://www.precursorintelligence.com/product/oracle/communications_billing_and_revenue_management_elastic_charging_engine) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 11.3, 12.0
- [Webcenter Portal](https://www.precursorintelligence.com/product/oracle/webcenter_portal) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 12.2.1.3.0, 12.2.1.4.0
- [Business Activity Monitoring](https://www.precursorintelligence.com/product/oracle/business_activity_monitoring) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 12.2.1.4.0
- [Commerce Guided Search](https://www.precursorintelligence.com/product/oracle/commerce_guided_search) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 11.3.2
- [Communications Cloud Native Core Automated Test Suite](https://www.precursorintelligence.com/product/oracle/communications_cloud_native_core_automated_test_suite) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 1.9.0
- [Communications Cloud Native Core Binding Support Function](https://www.precursorintelligence.com/product/oracle/communications_cloud_native_core_binding_support_function) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 1.10.0
- [Communications Cloud Native Core Policy](https://www.precursorintelligence.com/product/oracle/communications_cloud_native_core_policy) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 1.14.0
- [Snapmanager](https://www.precursorintelligence.com/product/netapp/snapmanager) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Application): version not specified
- [Utilities Testing Accelerator](https://www.precursorintelligence.com/product/oracle/utilities_testing_accelerator) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 6.0.0.1.1

## How do I fix CVE-2021-39144?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [oracle.com](https://www.oracle.com/security-alerts/cpuapr2022.html) (Patch, Third-party advisory)
- [oracle.com](https://www.oracle.com/security-alerts/cpujan2022.html) (Patch, Third-party advisory)
- [oracle.com](https://www.oracle.com/security-alerts/cpujul2022.html) (Patch, Third-party advisory)
- [github.com](https://github.com/x-stream/xstream/security/advisories/GHSA-j9h8-phrw-h4fh) (Vendor advisory)
- [x-stream.github.io](https://x-stream.github.io/CVE-2021-39144.html) (Exploit, Vendor advisory)
- [packetstormsecurity.com](http://packetstormsecurity.com/files/169859/VMware-NSX-Manager-XStream-Unauthenticated-Remote-Code-Execution.html) (Exploit, Third-party advisory, Vulnerability database)
- [lists.debian.org](https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html) (Mailing list, Third-party advisory)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/) (Mailing list, Release notes, Broken link)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/) (Mailing list, Release notes, Broken link)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/) (Mailing list, Release notes, Broken link)
- [security.netapp.com](https://security.netapp.com/advisory/ntap-20210923-0003/) (Third-party advisory)
- [debian.org](https://www.debian.org/security/2021/dsa-5004) (Third-party advisory)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-39144) (Government resource)

## Questions

### What is CVE-2021-39144?

CVE-2021-39144 is a high-severity flaw in Xstream, published on 23 August 2021. It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2021-39144?

It scores 8.5 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2021-39144 is 81 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2021-39144 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 98%.

### Which versions does CVE-2021-39144 affect?

For Xstream: before 1.4.18. The record lists 15 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2021-39144?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2021-39144 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

Start free (no card, nothing to install): https://www.precursorintelligence.com/register
Book a demo: https://www.precursorintelligence.com/contact