Security readout for executives and security teams
Plain-English summary
CVE-2026-0773 is a critical remote code execution flaw in Upsonic 0.52.1. An unauthenticated attacker who can reach the service’s add_tool endpoint, typically on TCP port 7541, may execute code as the service account. Treat internet-exposed or untrusted-network deployments as urgent.
Executive priority
Prioritize immediate exposure review. This is critical because exploitation is unauthenticated and can lead to code execution, but active exploitation is not confirmed in the supplied sources.
Technical view
The flaw is CWE-502 deserialization of untrusted data in Upsonic’s add_tool endpoint. ZDI reports Cloudpickle deserialization without proper validation, reachable remotely without authentication. Successful exploitation can affect confidentiality, integrity, and availability with CVSS 9.8 impact.
Likely exposure
Highest risk applies to Upsonic 0.52.1 installations where TCP port 7541 or the add_tool endpoint is reachable from untrusted networks. Exposure is lower if access is tightly restricted, but the source does not identify safe configurations.
Exploitation context
The advisory states exploitation requires network access, low complexity, no authentication, and no user interaction. The provided sources do not report active exploitation, and the CVE is not marked KEV in the supplied data.
Researcher notes
Evidence is centered on the CVE record and ZDI-26-042. The affected product/version listed is Upsonic 0.52.1. No patch version, workaround, proof-of-concept status, or exploitation-in-the-wild claim is provided in the supplied sources.
Mitigation direction
- Identify whether Upsonic 0.52.1 is deployed in your environment.
- Restrict access to TCP port 7541 and the add_tool endpoint to trusted systems only.
- Check Upsonic and ZDI guidance for patched versions or vendor-recommended workarounds.
- Run the service with least privileges to reduce impact if compromised.
- Monitor service logs and network telemetry for unexpected add_tool access.
Validation and detection
- Inventory Upsonic deployments and confirm version numbers.
- Review firewall, security group, and ingress rules for TCP port 7541.
- Confirm the add_tool endpoint is not reachable from the internet.
- Check whether the service account has excessive privileges.
- Track vendor advisories for a fixed release or official mitigation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-0773 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
9.8CriticalVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- ZDI-26-042CVE reference · x_research-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.