# CVE-2026-8739: Sanluan PublicCMS hard-coded cryptographic key in private file access

Source: https://junglewise.ai/threats/cve-2026-8739-sanluan-publiccms-hard-coded-cryptographic-key-in-private-file  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-17. Updated: 2026-05-17  
License: CC BY 4.0 with a link back

CVE-2026-8739 · Severity: medium · CVSS 5.3 · Published 2026-05-17

Sanluan PublicCMS, a content management system, contains a security flaw in how it protects private files. The system uses a predictable, hard-coded method to generate security keys for file access instead of using unique, random secrets. An attacker can exploit this to bypass security controls and download private documents or sensitive images without needing to log in.

Technologies: [Sanluan PublicCMS](https://junglewise.ai/threats/technologies/publiccms). Vendors: [Sanluan](https://junglewise.ai/threats/vendors/sanluan).

## Quick answers

**Is CVE-2026-8739 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-8739 being exploited in the wild.

**How severe is CVE-2026-8739?** Medium severity, with a CVSS score of 5.3, published 17 May 2026.

**Which products and versions are affected?** Sanluan PublicCMS 5.202506.d.

**Is there a fix for CVE-2026-8739?** 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-2026-8739 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-8739?** Check whether you run Sanluan PublicCMS 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

A cryptographic design flaw exists in the SafeConfigComponent.getSignKey function of Sanluan PublicCMS 5.202506.d. The application uses a deterministic fallback value for the 'privatefile_key' when it is not explicitly configured. This key is derived from predictable inputs, including the site ID and a cluster identifier that is publicly exposed via the '/api/directive/tools/version' endpoint. An unauthenticated remote attacker can obtain these inputs, derive the signing key offline, and forge valid signatures for the '/file/private' endpoint. This allows for the unauthorized download of any private file if the file path is known. The vendor has reportedly not responded to disclosure attempts.

## Affected products

- Sanluan PublicCMS 5.202506.d

## Timeline

- 2026-05-17: advisory: CVE-2026-8739 published via NVD/VulDB
- 2026-05-17: disclosed: Exploit code and technical analysis made public

## References

- [https://vuldb.com/submit/809917](https://vuldb.com/submit/809917)
- [https://vuldb.com/vuln/364327](https://vuldb.com/vuln/364327)
- [https://vuldb.com/vuln/364327/cti](https://vuldb.com/vuln/364327/cti)
- [https://vulnplus-note.wetolink.com/share/PCVUlOncmwTC](https://vulnplus-note.wetolink.com/share/PCVUlOncmwTC)

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