CVE-2020-1953Network attack vector

Code execution via unsafe YAML class instantiation

Published Mar 13, 2020 · Updated Aug 4, 2024

Uncontrolled class instantiation in Apache Commons Configuration 2.2 through 2.6 allows attackers to execute code through crafted YAML files. YAMLConfiguration.read creates SnakeYAML parsers with permissive constructors and passes input to Yaml.load, allowing explicit type tags to instantiate Java classes. An application must load an untrusted YAML file, and resulting code executes within the host application's process and privilege context.

CVSS severity10.0
Critical
EPSS probability6.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled class instantiation in Apache Commons Configuration 2.2 through 2.6 allows attackers to execute code through crafted YAML files. YAMLConfiguration.read creates SnakeYAML parsers with permissive constructors and passes input to Yaml.load, allowing explicit type tags to instantiate Java classes. An application must load an untrusted YAML file, and resulting code executes within the host application's process and privilege context.

The record

CVE
CVE-2020-1953
Published
Mar 13, 2020
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Commons Configuration
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 13, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.2
  2. Affected versionversion=2.3
  3. Affected versionversion=2.4
  4. Affected versionversion=2.5
  5. Affected versionversion=2.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Commons Configurationversion=2.2; version=2.3; version=2.4; version=2.5; version=2.6

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
10.0NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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