# CVE-2026-9191: Progress MarkLogic Server code isolation bypass in REST and XDBC

Source: https://junglewise.ai/threats/cve-2026-9191-progress-marklogic-server-12-x-releases-before-12-1-0-and-11-x  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-12. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-9191 · Severity: critical · CVSS 9.6 · Published 2026-10-12

Progress MarkLogic Server is a database platform used to store and query large volumes of semi-structured data in enterprise environments. Versions 12.x before 12.1.0 and 11.x before 11.3.7 fail to properly isolate user-supplied code executed through REST and XDBC evaluation endpoints, allowing an attacker to access HTTP request/response data and hijack authenticated sessions. An attacker with code execution capability on these endpoints could impersonate users, modify data, or access sensitive information.

Technologies: [Progress Marklogic Server](https://junglewise.ai/threats/technologies/marklogic-server). Vendors: [Progress](https://junglewise.ai/threats/vendors/progress).

## Quick answers

**Is CVE-2026-9191 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-9191 being exploited in the wild.

**How severe is CVE-2026-9191?** Critical severity, with a CVSS score of 9.6, published 12 October 2026.

**Which products and versions are affected?** Progress Marklogic Server 12.x before 12.1.0, 11.x before 11.3.7.

**Is there a fix for CVE-2026-9191?** Yes: fixed in MarkLogic Server 12.1.0, 11.3.7. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-9191 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-9191?** Check whether you run Progress Marklogic Server 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.

## How to fix

- Fixed in MarkLogic Server 12.1.0, 11.3.7

## Technical details

The vulnerability is a code isolation bypass in MarkLogic Server's REST and XDBC evaluation code paths that allows user-supplied code to access HTTP request, response, and session state that should be isolated. An attacker able to execute code through affected evaluation paths (such as REST endpoints or XDBC connections) can break out of the intended sandboxing to perform unauthorized actions or compromise authenticated sessions. The flaw requires an attacker to have code execution capability through these paths but no explicit authentication bypass is required if the endpoint itself is accessible.

## Affected products

- Progress MarkLogic Server 12.x before 12.1.0, 11.x before 11.3.7

## Timeline

- 2026-10-12: disclosed

## References

- [https://community.progress.com/s/article/Marklogic-Critical-Security-Alert-Bulletin-October-2026](https://community.progress.com/s/article/Marklogic-Critical-Security-Alert-Bulletin-October-2026)

## Related threats

- [Progress MarkLogic Server HTTP response splitting in Query Console](https://junglewise.ai/threats/cve-2026-85976-progress-marklogic-server-12-x-releases-before-12-1-0-and-11-x)
- [Progress MarkLogic Server cleartext S3 transport default](https://junglewise.ai/threats/cve-2026-85975-progress-marklogic-server-12-x-releases-before-12-1-0-and-11-x)
- [Progress MarkLogic Server TLS hostname validation bypass](https://junglewise.ai/threats/cve-2026-85974-progress-marklogic-server-12-x-releases-before-12-1-0-and-11-x)
- [Progress MarkLogic Server cleartext cluster-management communications](https://junglewise.ai/threats/cve-2026-85973-progress-marklogic-server-12-x-releases-before-12-1-0-may-use)
- [Progress MarkLogic Server Kerberos authentication verification bypass](https://junglewise.ai/threats/cve-2026-85972-progress-marklogic-server-12-x-releases-before-12-1-0-and-11-x)