Authenticated code execution via pickled continuation tokens
Published Jan 13, 2026 · Updated Jan 13, 2026
Deserialization in Microsoft Azure Core for Python 1.1.0 through 1.37.0 allows remote authenticated users to execute code via continuation tokens. The polling from_continuation_token path base64-decodes an attacker-controlled token and passes the bytes to pickle.loads, which reconstructs executable Python objects. Exploitation requires an authenticated remote user to supply a crafted continuation token to an application that restores Azure long-running-operation state, enabling code execution in that application's process.
Summary
What happened
Deserialization in Microsoft Azure Core for Python 1.1.0 through 1.37.0 allows remote authenticated users to execute code via continuation tokens. The polling from_continuation_token path base64-decodes an attacker-controlled token and passes the bytes to pickle.loads, which reconstructs executable Python objects. Exploitation requires an authenticated remote user to supply a crafted continuation token to an application that restores Azure long-running-operation state, enabling code execution in that application's process.
The record
- CVE
- CVE-2026-21226
- Published
- Jan 13, 2026
- Updated
- Jan 13, 2026
- Vendor
- Microsoft
- Product
- Azure Core shared client library for Python
- Classifications
- CWE-502
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 13, 2026CVE publishedPublication date reported by the CVE source.
- Jan 13, 2026Record 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=1.1.0 <1.38.0
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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