What is CVE-2026-0773?

CVE-2026-0773 is a critical-severity vulnerability in Upsonic, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-01-23.

How severe is CVE-2026-0773?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Deserialization in Upsonic

CVE-2026-0773

Upsonic Cloudpickle Deserialization of Untrusted Data Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Upsonic. Authentication is not required to exploit this vulnerability. The specific flaw exists within the add_tool endpoint, which listens on TCP port 7541 by default. The issue results from the lack of proper validation of user-supplied data, which can result in deserialization of untrusted data. An attacker can leverage this vulnerability to execute code in the context of the service account. Was ZDI-CAN-26845.

Vulnerability class: Insecure Deserialization

EPSS: 0.011 (63.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Upsonic — versions 0.52.1

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

zdi-disclosures@trendmicro.com (x_research-advisory)

Frequently asked questions

What is CVE-2026-0773?: CVE-2026-0773 is a critical-severity vulnerability in Upsonic, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-01-23.
How severe is CVE-2026-0773?: Critical severity. CVSS v3 base score is 9.8 out of 10.