Is CVE-2026-51859 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-51859 being exploited in the wild.

How severe is CVE-2026-51859?

Informational severity, published 30 September 2026.

Which products and versions are affected?

Dataelement BISHENG 2.3.0, 2.4.0, 2.4.0-beta1.

Is there a fix for CVE-2026-51859?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-51859 attacked?

It is attacked over the network.

Am I affected by CVE-2026-51859?

Check whether you run Dataelement BISHENG at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-51859: bisheng directory traversal in save_download_file

CVE-2026-51859 · Severity: info · Published 2026-09-30

bisheng is an open-source platform for building AI applications. A directory traversal vulnerability in its file upload functionality allows attackers to write files outside the intended cache directory, potentially enabling remote code execution or data corruption. An attacker can upload a file with a specially crafted filename containing path traversal sequences to place malicious content anywhere the application has write permissions.

Technologies: Dataelement BISHENG. Vendors: Dataelement.

Quick answers

Is CVE-2026-51859 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-51859 being exploited in the wild.
How severe is CVE-2026-51859?: Informational severity, published 30 September 2026.
Which products and versions are affected?: Dataelement BISHENG 2.3.0, 2.4.0, 2.4.0-beta1.
Is there a fix for CVE-2026-51859?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-51859 attacked?: It is attacked over the network.
Am I affected by CVE-2026-51859?: Check whether you run Dataelement BISHENG at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The save_download_file function in src/backend/bisheng/core/cache/utils.py constructs file paths by concatenating user-supplied filenames without proper sanitization. Although it truncates long filenames to 60 characters, it does not strip path traversal sequences like "../". When combined with the knowledgeUpload endpoint, an attacker can inject traversal sequences in the filename parameter to escape the cache directory and write files to arbitrary locations accessible by the application process.

Affected products

DataElement bisheng 2.3.0, 2.4.0, 2.4.0-beta1

Timeline

2026-09-30: disclosed
2026-04-20: other: Vulnerability details published on GitHub issue #1994

References

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