CVE-2026-34839

Description

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.

CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-200 CWE-200

CWE-306 Missing Authentication

CWE-942 CWE-942

Affected Products

Vendor	Product	Versions
nicolargo	glances	< 4.5.4

References

Advisories & Patches

https://github.com/nicolargo/glances/commit/fdfb977b1d91b5e410bc06c4e19f8bedb0005ce9 https://github.com/nicolargo/glances/security/advisories/GHSA-gfc2-9qmw-w7vh https://github.com/nicolargo/glances/security/advisories/GHSA-gfc2-9qmw-w7vh

Exploits

https://github.com/nicolargo/glances/security/advisories/GHSA-gfc2-9qmw-w7vh https://github.com/nicolargo/glances/security/advisories/GHSA-gfc2-9qmw-w7vh

Frequently Asked Questions

What is CVE-2026-34839? +

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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-34839? +

CVE-2026-34839 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-34839? +

CVE-2026-34839 affects products from nicolargo, specifically: glances. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-34839? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-15625

Unauthenticated user is able to execute arbitrary SQL commands in Sparx Pro Cloud Server database in certain cases.

CVE-2026-22051

StorageGRID (formerly StorageGRID Webscale) versions prior to 11.9.0.13 and 12.0.0.6 are susceptible to a Information Disclosure vulnerability. Successful exploit could …

CVE-2026-40166

authentik is an open-source identity provider. In versions prior to 2025.12.5 and 2026.2.0-rc1 through 2026.2.2, authenticated non-admin users with at …

CVE-2025-22138

@codidact/qpixel is a Q&A-based community knowledge-sharing software. In affected versions when a category is set to private or limited-visibility within …

CVE-2025-0659

A path traversal vulnerability exists in the Rockwell Automation DataEdge Platform DataMosaix Private Cloud. By specifying the character sequence in …

CVE-2025-24884

kube-audit-rest is a simple logger of mutation/creation requests to the k8s api. If the "full-elastic-stack" example vector configuration was used …