CVE-2026-5559
CVE-2026-5559 is a medium-severity vulnerability with a CVSS 3.x base score of 6.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-791.
Key facts
- Severity: Medium (CVSS 3.x base score 6.3)
- CVSS v2: 6.5
- CVSS v4: 2.1
- EPSS exploit prediction: 0% (23rd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-19066
- Weakness: CWE-791
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-5559?
- 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.
- How severe is CVE-2026-5559?
- CVE-2026-5559 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
- Is CVE-2026-5559 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-5559?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-5559 have an EU (EUVD) identifier?
- Yes. CVE-2026-5559 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19066.
- When was CVE-2026-5559 published?
- CVE-2026-5559 was published on 2026-04-05 and last updated on 2026-06-17.
References
- https://github.com/AntaresMugisho/PyBlade/
- https://github.com/AntaresMugisho/PyBlade/issues/1
- https://github.com/AntaresMugisho/PyBlade/issues/1#issue-4086730906
- https://vuldb.com/submit/782904
- https://vuldb.com/vuln/355329
- https://vuldb.com/vuln/355329/cti
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