CVE-2026-5559 — pyblade
CVE-2026-5559 is a CWE-791 vulnerability in pyblade. No vendor fix is recorded yet; mitigation options are listed below.
AntaresMugisho PyBlade AST Validation sandbox.py _is_safe_ast special elements used in a template engine
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-5559.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
pybladeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
A vulnerability has been found in AntaresMugisho PyBlade 0.1.8-alpha/0.1.9-alpha. The affected element is the function _is_safe_ast of the file sandbox.py of the component AST Validation. Such manipulation leads to improper neutralization of special elements used in a template engine. The attack may be performed from remote. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pyblade | ≥ 0.1.8-alpha | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyblade, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of pyblade has shipped for CVE-2026-5559 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-5559 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-5559. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-5559 in your dependencies?
O3 Security finds CVE-2026-5559 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.