{"id":"CVE-2026-45694","aliases":["EUVD-2026-66772","GHSA-jmqm-f8q4-v7wx"],"status":"published","title":"LibreNMS: Reflected XSS in the Proxmox app view via unsanitized instance/vmid parameters","description":"LibreNMS is a network monitoring system. In versions up to and including 26.4.0, the Proxmox application view is vulnerable to reflected cross-site scripting through the user-supplied instance and vmid GET parameters, which are reflected into the page title without adequate encoding. The parameters are placed into the page title with only strip_tags applied, and the title is then written into an inline document.title assignment through string interpolation, so a single quote terminates the JavaScript string and the remaining input runs as script. An attacker who lures an authenticated user into following a crafted link can execute script in that user's session, enabling actions such as theft of session data. This issue is fixed in version 26.5.0.","severity":{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00235,"percentile":0.14536,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-79"],"published":"2026-08-12T15:16:22Z","modified":"2026-10-28T02:30:35Z","fixes":[{"ecosystem":"Packagist","package":"librenms/librenms","fixed_in":["26.5.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Packagist","package":"librenms/librenms","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"26.4.0"},{"fixed":"26.5.0"}]}]},{"source":"osv","ecosystem":"Packagist","package":"librenms/librenms","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"26.5.0"}]}],"versions":["1.19","1.20","1.20.1","1.21","1.22","1.22.01","1.23","1.24","1.25","1.26","1.27","1.28","1.29","1.30","1.30.01","1.31","1.31.01","1.31.02","1.31.03","1.32","1.32.01","1.33","1.33.01","1.34","1.35","1.36","1.36.01","1.37","1.38","1.39","1.40","1.41","1.42","1.42.01","1.43","1.44","1.45","1.46","1.47","1.48","1.48.1","1.49","1.50","1.50.1","1.51","1.52","1.53","1.53.1","1.54","1.55","1.56","1.57","1.58","1.58.1","1.59","1.60","1.61","1.62","1.62.1","1.62.2","1.63","1.64","1.64.1","1.65","1.65.1","1.66","1.67","1.68","1.69","1.70.0","1.70.1","21.1.0","21.10.0","21.10.1","21.10.2","21.11.0","21.12.0","21.12.1","21.2.0","21.3.0","21.4.0","21.5.0","21.5.1","21.6.0","21.7.0","21.8.0","21.9.0","21.9.1","22.1.0","22.10.0","22.11.0","22.12.0","22.2.0","22.2.1","22.2.2","22.3.0","22.4.0","22.4.1","22.5.0","22.6.0","22.7.0","22.8.0","22.9.0","23.1.0","23.1.1","23.10.0","23.11.0","23.2.0","23.4.0","23.4.1","23.5.0","23.6.0","23.7.0","23.8.0","23.8.1","23.8.2","23.9.0","23.9.1","24.1.0","24.10.0","24.10.1","24.11.0","24.12.0","24.2.0","24.3.0","24.4.0","24.4.1","24.5.0","24.6.0","24.7.0","24.8.0","24.8.1","24.9.0","24.9.1","25.1.0","25.10.0","25.11.0","25.12.0","25.2.0","25.3.0","25.4.0","25.5.0","25.6.0","25.7.0","25.8.0","25.9.0","25.9.1","26.1.0","26.1.1","26.2.0","26.3.0","26.3.1","26.4.0","26.4.1"]}],"products":[{"vendor":"librenms","product":"librenms"}],"references":[{"url":"https://github.com/librenms/librenms/security/advisories/GHSA-jmqm-f8q4-v7wx","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/librenms/librenms/commit/0be1bfd7746cea26bf7da40e82b70f75b724d0f8","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/librenms/librenms/releases/tag/26.5.0","tags":["web"]},{"url":"https://github.com/advisories/GHSA-jmqm-f8q4-v7wx"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45694.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45694","tags":["advisory"]},{"url":"https://github.com/librenms/librenms","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-45694","title":"LibreNMS: Reflected XSS in the Proxmox app view via unsanitized instance/vmid parameters","description":"LibreNMS is a network monitoring system. In versions up to and including 26.4.0, the Proxmox application view is vulnerable to reflected cross-site scripting through the user-supplied instance and vmid GET parameters, which are reflected into the page title without adequate encoding. The parameters are placed into the page title with only strip_tags applied, and the title is then written into an inline document.title assignment through string interpolation, so a single quote terminates the JavaScript string and the remaining input runs as script. An attacker who lures an authenticated user into following a crafted link can execute script in that user's session, enabling actions such as theft of session data. This issue is fixed in version 26.5.0.","status":"published","published":"2026-08-26T21:42:01.423Z","modified":"2026-08-27T14:32:34.046Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T13:46:43.922571Z"}],"euvd":[{"id":"EUVD-2026-66772","description":"LibreNMS is a network monitoring system. In versions up to and including 26.4.0, the Proxmox application view is vulnerable to reflected cross-site scripting through the user-supplied instance and vmid GET parameters, which are reflected into the page title without adequate encoding. The parameters are placed into the page title with only strip_tags applied, and the title is then written into an inline document.title assignment through string interpolation, so a single quote terminates the JavaScript string and the remaining input runs as script. An attacker who lures an authenticated user into following a crafted link can execute script in that user's session, enabling actions such as theft of session data. This issue is fixed in version 26.5.0.","status":"published","published":"2026-08-26T21:42:01Z","modified":"2026-08-27T14:32:34Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T18:01:28.115205Z"}],"ghsa":[{"id":"GHSA-jmqm-f8q4-v7wx","title":"LibreNMS: Reflected XSS via Proxmox instance/vmid GET parameters injected into document.title JavaScript assignment","description":"### Summary\n`LegacyController.php:75` writes the page title into a `document.title` JS assignment using string interpolation. `apps/proxmox.inc.php` pushes `$vars['instance']` and `$vars['vmid']` (GET params, only `strip_tags()` applied) directly into `$pagetitle`. A single quote terminates the JS string, executing arbitrary script.\n\n### Details\n```php\n// LegacyController.php:75\n$html .= \"\u003cscript\u003e\\ndocument.title = '$title';\\n\u003c/script\u003e\";\n\n// proxmox.inc.php:38,42\n$pagetitle[] = $instance;     // GET ?instance=\n$pagetitle[] = $vars['vmid']; // GET ?vmid=\n```\n\n### PoC\n```\nhttp://target/apps?app=proxmox\u0026instance=%27%3Balert%28document.cookie%29%3B//\n\nConfirmed in response:\ndocument.title = 'Apps - Proxmox - ';alert(document.cookie);// - LibreNMS';\n```\n\n### Fix\n```php\n// LegacyController.php:75\n$html .= \"\u003cscript\u003e\\ndocument.title = \" . json_encode($title) . \";\\n\u003c/script\u003e\";\n```\nAlso wrap `$instance` and `$vars['vmid']` in `htmlspecialchars()` in proxmox.inc.php.\n\n### Prerequisite\nAny authenticated session. Victim must follow a crafted link.","status":"published","published":"2026-08-12T15:16:22Z","modified":"2026-08-12T15:16:25Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:40:58.888637Z"}],"nvd":[{"id":"CVE-2026-45694","description":"LibreNMS is a network monitoring system. In versions up to and including 26.4.0, the Proxmox application view is vulnerable to reflected cross-site scripting through the user-supplied instance and vmid GET parameters, which are reflected into the page title without adequate encoding. The parameters are placed into the page title with only strip_tags applied, and the title is then written into an inline document.title assignment through string interpolation, so a single quote terminates the JavaScript string and the remaining input runs as script. An attacker who lures an authenticated user into following a crafted link can execute script in that user's session, enabling actions such as theft of session data. This issue is fixed in version 26.5.0.","status":"published","published":"2026-08-26T22:16:24.793Z","modified":"2026-09-09T21:09:13.08Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:12:41.66469Z"}],"osv":[{"id":"CVE-2026-45694","title":"LibreNMS: Reflected XSS in the Proxmox app view via unsanitized instance/vmid parameters","description":"LibreNMS is a network monitoring system. In versions up to and including 26.4.0, the Proxmox application view is vulnerable to reflected cross-site scripting through the user-supplied instance and vmid GET parameters, which are reflected into the page title without adequate encoding. The parameters are placed into the page title with only strip_tags applied, and the title is then written into an inline document.title assignment through string interpolation, so a single quote terminates the JavaScript string and the remaining input runs as script. An attacker who lures an authenticated user into following a crafted link can execute script in that user's session, enabling actions such as theft of session data. This issue is fixed in version 26.5.0.","status":"published","published":"2026-08-26T21:42:01.423Z","modified":"2026-10-28T02:30:35.391213147Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:45:05.525666Z"},{"id":"GHSA-jmqm-f8q4-v7wx","title":"LibreNMS: Reflected XSS via Proxmox instance/vmid GET parameters injected into document.title JavaScript assignment","description":"### Summary\n`LegacyController.php:75` writes the page title into a `document.title` JS assignment using string interpolation. `apps/proxmox.inc.php` pushes `$vars['instance']` and `$vars['vmid']` (GET params, only `strip_tags()` applied) directly into `$pagetitle`. A single quote terminates the JS string, executing arbitrary script.\n\n### Details\n```php\n// LegacyController.php:75\n$html .= \"\u003cscript\u003e\\ndocument.title = '$title';\\n\u003c/script\u003e\";\n\n// proxmox.inc.php:38,42\n$pagetitle[] = $instance;     // GET ?instance=\n$pagetitle[] = $vars['vmid']; // GET ?vmid=\n```\n\n### PoC\n```\nhttp://target/apps?app=proxmox\u0026instance=%27%3Balert%28document.cookie%29%3B//\n\nConfirmed in response:\ndocument.title = 'Apps - Proxmox - ';alert(document.cookie);// - LibreNMS';\n```\n\n### Fix\n```php\n// LegacyController.php:75\n$html .= \"\u003cscript\u003e\\ndocument.title = \" . json_encode($title) . \";\\n\u003c/script\u003e\";\n```\nAlso wrap `$instance` and `$vars['vmid']` in `htmlspecialchars()` in proxmox.inc.php.\n\n### Prerequisite\nAny authenticated session. Victim must follow a crafted link.","status":"published","published":"2026-08-12T15:16:22Z","modified":"2026-08-12T15:41:04.197622Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:46:50.687609Z"}]}}