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CVE-2021-39144

XStream is vulnerable to a Remote Command Execution attack

Exploited in the wild. In CISA KEV since 2023‑03‑10. A vendor fix is available.

CVSS 3.18.5HighEPSS percentile99th98% chance in 30 daysCISA KEVListedsince 2023-03-10, due 2023-03-31
Public exploit: 1 sourceFixVendor fixNo build named by the sources

Published Updated Sources: CVE.org, NVD, GitHub, BDU

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Check it yourselfA free Nuclei and OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Discuss checks for your systems with a specialist. Scope is agreed before testing.

What it is

From the CVE record

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.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS99th
Public exploit
CISA KEV
CISA KEV

Listed as exploited in the wild since 2023-03-10.

US federal agencies must remediate by 2023-03-31.

Apply updates per vendor instructions.
Public exploits

1 source with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

98% chance of exploitation activity in the next 30 days, which ranks it in the 99th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 133 days before any public exploit.

  1. OpenVAS check added
  2. Public exploit / PoCsource: packetstormnuclei check added
  3. Patch availablerecord updated
  4. Added to CISA KEV
  5. Publishedweakness classified, att&ck mapped

Affected products

And 19 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 8.5 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 31 more references. See all after sign-in

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