CVE-2021-39144

XStream: Remote Code Execution

As of , CVE-2021-39144 in XStream is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 10 March 2023
US federal deadline
31 March 202321 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.98Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
0.96 on 10 March 2023EPSS on the day CISA listed it.
Public exploit
1 Metasploit module
Fix
Vendor advice: www.vmware.comLinks below, from CISA's entry.

What CISA says to do

Apply updates per vendor instructions.

CISA's required action

What the flaw is

XStream contains a remote code execution vulnerability that allows an attacker to manipulate the processed input stream and replace or inject objects that result in the execution of a local command on the server. This vulnerability can affect multiple products, including but not limited to VMware Cloud Foundation.

CISA's 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.

The CVE record's description, from GitHub_M

CVE published
23 August 2021
Assigned by
GitHub_M
CVSS
8.5 High (CVSS 3.1, from the CNA)
CWE-94
Improper Control of Generation of Code ('Code Injection')
CWE-502
Deserialization of Untrusted Data
CISA SSVC, exploitation
active
CISA SSVC, automatable
no
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

  • Metasploit: VMware NSX Manager XStream unauthenticated RCEexploit module, rank excellent

Read further