# CVE-2026-34839: Glances: Cross-Origin Information Disclosure via Unauthenticated REST API (/api/4) due to Permissive CORS

Source: https://junglewise.ai/threats/cve-2026-34839-glances-cross-origin-information-disclosure-via-unauthenticated  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-21  
License: CC BY 4.0 with a link back

CVE-2026-34839 · Severity: medium · CVSS 6.5 · Published 2026-04-21

Glances is an open-source system cross-platform monitoring tool. Prior to version 4.5.4, the Glances web server exposes a REST API (`/api/4/*`) that is accessible without authentication and allows cross-origin requests from any origin due to a permissive CORS policy (`Access-Control-Allow-Origin: *`). This allows a malicious website to read sensitive system information from a running Glances instance in the victim’s browser, leading to cross-origin data exfiltration. While a previous advisory exists for XML-RPC CORS issues, this report demonstrates that the REST API (`/api/4/*`) is also affected and exposes significantly more sensitive data. Version 4.5.4 patches the issue.

Technologies: [Nicolargo Glances](https://junglewise.ai/threats/technologies/nicolargo-glances), [glances (PyPI)](https://junglewise.ai/threats/technologies/glances). Vendors: [Nicolargo](https://junglewise.ai/threats/vendors/nicolargo), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-34839 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34839 being exploited in the wild.

**How severe is CVE-2026-34839?** Medium severity, with a CVSS score of 6.5, published 21 April 2026.

**Which products and versions are affected?** glances (PyPI) ECOSYSTEM:introduced=0,fixed=4.5.4.

**Is there a fix for CVE-2026-34839?** Yes. glances (PyPI): upgrade to 4.5.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-34839?** Check whether you run Nicolargo Glances or glances (PyPI) 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

- glances (PyPI): upgrade to 4.5.4 or later

  ```sh
  pip install "glances>=4.5.4"
  ```


## Affected products

- Nicolargo Glances
- glances (PyPI) ECOSYSTEM:introduced=0,fixed=4.5.4

## Identifiers

- CVE-2026-34839
- GHSA-gfc2-9qmw-w7vh
- PYSEC-2026-2175

## Related threats

- [Glances as_dict_secure credential leak in API config endpoint](https://junglewise.ai/threats/cve-2026-68520-glances-as-dict-secure-credential-leak-in-api-config-endpoint)
- [Glances incomplete fix in alert action command execution](https://junglewise.ai/threats/cve-2026-68519-glances-incomplete-fix-in-alert-action-command-execution)
- [Glances incomplete command injection sanitizer fix in nested stat values](https://junglewise.ai/threats/cve-2026-62982-glances-incomplete-command-injection-sanitizer-fix-in-nested-stat)
- [Glances command injection via cross-field shell-operator reconstruction](https://junglewise.ai/threats/cve-2026-68518-glances-command-injection-via-cross-field-shell-operator)
- [Glances REST API CORS credentials bypass via wildcard in multi-origin list](https://junglewise.ai/threats/cve-2026-68517-glances-rest-api-cors-credentials-bypass-via-wildcard-in-multi)