---
id: "CVE-2026-123783"
page: "https://infrastack.ai/live/CVE-2026-123783"
kind: "vulnerability"
aliases: ["CVE-2026-123783"]
title: "Skyvern: sandbox bypass lets logged-in users run code on server"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "ai-tooling"
products: []
ecosystems: []
tags: ["ai-browser-automation", "ai-tooling", "python", "self-hosted", "skyvern"]
not_affected_if: ["auth-required", "managed-hosting", "no-user-scripts"]
published_at: "2026-11-06T15:17:21+00:00"
first_seen_at: "2026-11-06T15:42:44+00:00"
updated_at: "2026-11-06T15:43:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123783", "first_seen_at": "2026-11-06T15:42:44+00:00"}]
exploit_sources: []
---

# Skyvern: sandbox bypass lets logged-in users run code on server

Link for people: https://infrastack.ai/live/CVE-2026-123783 (this .md is for agents)

Skyvern, an AI browser automation tool, has a sandbox escape in its script runner: authenticated users can rebuild functions from raw bytecode to evade the AST denylist. A successful attacker runs arbitrary code inside the Skyvern server process, including importing blocked modules like subprocess and socket.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Skyvern version against the ranges in the NVD entry (affected through `1.0.56`)
- Confirm whether users can deploy or run custom scripts on your Skyvern instance

## Fix

- Move to a Skyvern release newer than `1.0.56` (the fixed version is not stated in the sources; see the linked patch)

## Timeline

- 2026-11-06T15:42:44+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123783

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/skyvern-through-1.0.56-script-sandbox-bypass-via-types-codetype-bytecode
- [fix] Patch: github.com https://github.com/Skyvern-AI/skyvern/commit/31a64c1a4b5dfaf1e76a7164845e10f2d68248dc

## From the sources

Skyvern through 1.0.56 contains a sandbox bypass vulnerability that allows authenticated users to execute code by reconstructing functions from raw bytecode with types.CodeType. Attackers can deploy scripts that evade the is_safe_script_code AST denylist and import blocked modules such as subprocess or socket to run code in the Skyvern server process.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_