Code execution via attacker-controlled object state
Published Mar 24, 2020 · Updated Aug 4, 2024
Code execution in PyYAML 5.1b7 through 5.3 allows remote attackers to run arbitrary code by supplying YAML to FullLoader. FullConstructor.set_python_instance_state accepts attacker-controlled state keys, letting construct_python_object_apply invoke extend or special methods during object initialization. Exposure requires an application to parse attacker-controlled YAML with full_load or FullLoader; successful exploitation runs code with that application's privileges.
Summary
What happened
Code execution in PyYAML 5.1b7 through 5.3 allows remote attackers to run arbitrary code by supplying YAML to FullLoader. FullConstructor.set_python_instance_state accepts attacker-controlled state keys, letting construct_python_object_apply invoke extend or special methods during object initialization. Exposure requires an application to parse attacker-controlled YAML with full_load or FullLoader; successful exploitation runs code with that application's privileges.
The record
- CVE
- CVE-2020-1747
- Published
- Mar 24, 2020
- Updated
- Aug 4, 2024
- Vendor
- PyYAML
- Product
- PyYAML
- Classifications
- CWE-20
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 24, 2020CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=5.3.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Upstream python/object/new regression payloadproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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