Unauthenticated code execution via cloudpickle deserialization
Published Jan 23, 2026 · Updated Jan 23, 2026
Deserialization of untrusted data in Upsonic 0.52.1 allows remote attackers to execute arbitrary code through the add_tool endpoint. The endpoint accepts a base64-encoded function value in a JSON POST body and passes decoded attacker-controlled bytes directly to cloudpickle.loads without validation. No authentication or user interaction is required; successful exploitation runs code with the Upsonic service account's privileges.
Summary
What happened
Deserialization of untrusted data in Upsonic 0.52.1 allows remote attackers to execute arbitrary code through the add_tool endpoint. The endpoint accepts a base64-encoded function value in a JSON POST body and passes decoded attacker-controlled bytes directly to cloudpickle.loads without validation. No authentication or user interaction is required; successful exploitation runs code with the Upsonic service account's privileges.
The record
- CVE
- CVE-2026-0773
- Published
- Jan 23, 2026
- Updated
- Jan 23, 2026
- Vendor
- Upsonic
- Product
- Upsonic
- Classifications
- CWE-502, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 23, 2026CVE publishedPublication date reported by the CVE source.
- Jan 23, 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=0.52.1
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
- Upsonic cloudpickle RCE Metasploit modulefunctional · demonstrated
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Technologies
Your stack
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Your stack
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