CVE-2021-23338Public exploit

Code execution via crafted workflow YAML

Published Feb 15, 2021 · Updated Sep 16, 2024

Deserialization in Qlib before 0.7.0 allows attackers to execute arbitrary Python code through a crafted workflow YAML file. The published proof of concept invokes qlib.workflow.cli.workflow with a YAML object tag, while the corrective commit replaces yaml.load with yaml.safe_load in qlib/workflow/cli.py. Execution requires a local process to load the attacker-controlled file; Snyk now states that the advisory does not affect qlib and deems it not a vulnerability.

CVSS severity7.2
High
EPSS probability3.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Deserialization in Qlib before 0.7.0 allows attackers to execute arbitrary Python code through a crafted workflow YAML file. The published proof of concept invokes qlib.workflow.cli.workflow with a YAML object tag, while the corrective commit replaces yaml.load with yaml.safe_load in qlib/workflow/cli.py. Execution requires a local process to load the attacker-controlled file; Snyk now states that the advisory does not affect qlib and deems it not a vulnerability.

The record

CVE
CVE-2021-23338
Published
Feb 15, 2021
Updated
Sep 16, 2024
Vendor
Microsoft
Product
Qlib
Classifications
CWE-502, T1059.006
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Feb 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <unspecified

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Microsoft · Qlibversion=0 <unspecified

Published CVSS scores

6.5NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
6.6SnykCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
7.2NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/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)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1059.006Python

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo