CVE-2026-123783 (CVSS 8.8)

Description

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.

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0056

Probability of exploitation

0.47%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-184 CWE-184

References

Other References

https://github.com/Skyvern-AI/skyvern https://github.com/Skyvern-AI/skyvern/blob/v1.0.56/skyvern/forge/sdk/workflow/code_block_safety.py#L106-L142 https://github.com/Skyvern-AI/skyvern/blob/v1.0.56/skyvern/forge/sdk/workflow/service.py#L1509-L1511 https://github.com/Skyvern-AI/skyvern/commit/31a64c1a4b5dfaf1e76a7164845e10f2d68248dc https://github.com/Skyvern-AI/skyvern/issues/8927 https://github.com/Skyvern-AI/skyvern/pull/8937 https://www.vulncheck.com/advisories/skyvern-through-1.0.56-script-sandbox-bypass-via-types-codetype-bytecode

Frequently Asked Questions

What is CVE-2026-123783? +

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. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-123783? +

CVE-2026-123783 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0056, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-123783? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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