CVE-2026-34839 is a high-severity missing authentication for critical function vulnerability in Glances (pip), affecting versions < 4.5.4. It is fixed in 4.5.4.
Summary 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. Details When Glances is started in web mode (e.g., glances -w -B 0.0.0.0), it exposes a REST API endpoint at: http://<host>:61208/api/4/all The server responds with: Access-Control-Allow-Origin: This allows any origin to perform cross-origin requests and read responses. The /api/4/all endpoint returns extensive system information, including: Process list (processlist) System details (hostname, OS, CPU info) Memory and disk usage Network interfaces and IP address Running services and metrics Because no authentication is required by default, this data is accessible to any web page. PoC Start Glances: glances -w -B 0.0.0.0 Create a malicious HTML file: Open the file in a browser while Glances is running. Observe that the browser successfully retrieves sensitive system information from the API. This works cross-origin (e.g., from file:// or attacker-controlled domains). Impact A remote attacker can host a malicious website that, when visited by a victim running Glances, can: Read sensitive system information Enumerate running processes Identify network configuration and IP addresses Fingerprint the host system This requires no authentication and no user interaction beyond visiting a web page. This represents a cross-origin information disclosure vulnerability and can aid further attacks such as reconnaissance or targeted exploitation.
A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.
CVE-2026-34839 has a CVSS score of 6.5 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (4.5.4). Upgrading removes the vulnerable code path.
pip
Glances (< 4.5.4)Glances → 4.5.4 (pip)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-34839 is reachable in your applications. Explore open-source security for your team.
See if CVE-2026-34839 is reachable in your applications. Get a demo
Already deployed Kodem? See CVE-2026-34839 in your environment →Upgrade Glances to 4.5.4 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-34839 is a high-severity missing authentication for critical function vulnerability in Glances (pip), affecting versions < 4.5.4. It is fixed in 4.5.4. A critical operation is accessible without requiring any authentication.
CVE-2026-34839 has a CVSS score of 6.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Glances (pip) versions < 4.5.4 is affected.
Yes. CVE-2026-34839 is fixed in 4.5.4. Upgrade to this version or later.
Whether CVE-2026-34839 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade Glances to 4.5.4 or later.