CVE-2026-31220
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedPySyft (Syft Datasite/Server) versions 0.9.5 and earlier are vulnerable to remote code execution due to insufficient validation and sandboxing of user-submitted code. The system allows low-privileged users to submit Python functions (via @sy.syft_function()) for remote execution on the server. While a code approval mechanism exists, the submitted code undergoes no security checks for dangerous operations (e.g., file access, command execution). Once approved, the code is executed within the server process using exec() and eval() functions without proper isolation. A remote attacker can leverage this to execute arbitrary Python code on the server, leading to complete compromise of the server environment.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencePySyft versions 0.9.5 and earlier allows low-privileged users to submit Python functions via @sy.syft_function() for server-side execution. Although a code approval workflow exists, no security validation checks for dangerous operations (file I/O, command execution) are performed. Approved code executes within the server process using exec() and eval() without sandboxing or isolation, enabling arbitrary Python code execution and full server compromise.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed PySyft versionRun `pip show pysyft` or `python -c "import syft; print(syft.__version__)"`Affected if Version is 0.9.5 or lower
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Identify use of @sy.syft_function decoratorSearch codebase for `@sy.syft_function` or `syft_function` usage in Python files: `grep -r "syft_function" .`Affected if The decorator is present and exposed to low-privileged users
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Verify code execution uses exec() or eval()Search source code for exec or eval calls handling user-submitted functions: `grep -r "exec(\|eval(" .`Affected if exec() or eval() is used to run user-submitted code without sandboxing
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Check for input validation on submitted functionsInspect the code approval workflow implementation for security checks on file I/O, os.system, subprocess, or other dangerous modulesAffected if No validation exists for dangerous operations before execution
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Confirm execution runs in server processReview the function execution path to verify user code runs within the main PySyft server process rather than an isolated subprocess or containerAffected if User code executes in the same process as the server
You are affected if running PySyft 0.9.5 or earlier and low-privileged users can submit @sy.syft_function() decorated code that runs via exec/eval without sandboxing or security validation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement strict input validation and sandboxing for user-submitted code before execution, preferably using isolated containers or restricted Python interpreters (e.g., sandboxed subprocesses, restricted Python environments). Disable direct use of exec() and eval() on untrusted code, or upgrade to a version that addresses these deficiencies.
- Consultation8.0 h
- Implementation40.0 h
- Testing16.0 h
- Review / QA12.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-31220 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-31220 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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