RCE in Up9inc Pybars4
CVE-2026-119717
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.
Vulnerability class: RCE (Remote Code Execution)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/vladko312/advisories/blob/702e98db9642ece70d9e2150076d8014ffec2db3/p… (third-party-advisory)
- github.com/up9inc/pybars4/blob/0.9.13/pybars/_compiler.py (technical-description)
- github.com/up9inc/pybars4 (product)
- www.vulncheck.com/advisories/pybars4-through-0.9.13-code-injection-via-brackete… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-119717?
- CVE-2026-119717 is a high-severity vulnerability in Up9inc Pybars4, classified under Code Injection. CVSS score: 8.1/10. Published 2026-10-30.
- How severe is CVE-2026-119717?
- High severity. CVSS v3 base score is 8.1 out of 10.