Skyvern through 1.0.56 Script Sandbox Bypass via types.CodeType Bytecode
Skyvern 1.0.56 and earlier, where the Scripts feature runs uploaded Python with the AST check is_safe_script_code as its only gate. No fixed version appears in the checked facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Skyvern Scripts feature runs uploaded Python files as an importlib-loaded module; the AST check is_safe_script_code is the only gate Affected versions are through 1.0.56 (per CVE advisory)
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 18/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
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.
cve.now Index
- Exploitation0/40No signal
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.7/10CVSS 8.7, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 25 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Skyvern Scripts feature runs uploaded Python files as an importlib-loaded module; the AST check is_safe_script_code is the only gate Affected versions are through 1.0.56 (per CVE advisory)Apply the patch listed under Evidence.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Skyvern-AI skyvern
through 1.0.56
Evidence 7
- Patch
- Patch
- Report
- Repository
- Repository
Show all 7 sourcesShow fewer sources
- Repository
- Link
Corrections
None so far.
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Questions about CVE-2026-123783
Is CVE-2026-123783 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Authenticated users can build functions from raw bytecode using types.CodeType, which evades the AST denylist. This lets them import blocked modules such as subprocess or socket and run code in the Skyvern server process.Source: github.com, vulncheck.com
Which versions are affected by CVE-2026-123783?
skyvern: through 1.0.56.Source: cve.now feed data
Am I affected, and how do I check?
Versions through 1.0.56 are affected, per the CVE advisory. To check a installation, look at the installed Skyvern version and whether the Scripts feature is in use.Source: github.com, vulncheck.com
How do I fix CVE-2026-123783?
The checked facts do not name a fixed version, so no upgrade target can be given from them. Check the vendor advisory or release notes for a patched release.Source: github.com, vulncheck.com