GHSA-jmqm-f8q4-v7wx

Suggest an improvement
Source
https://github.com/advisories/GHSA-jmqm-f8q4-v7wx
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-jmqm-f8q4-v7wx/GHSA-jmqm-f8q4-v7wx.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-jmqm-f8q4-v7wx
Aliases
Published
2026-08-12T15:16:22Z
Modified
2026-08-12T15:41:04Z
Severity
  • 5.4 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N CVSS Calculator
Summary
LibreNMS: Reflected XSS via Proxmox instance/vmid GET parameters injected into document.title JavaScript assignment
Details

Summary

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.

Details

// LegacyController.php:75
$html .= "<script>\ndocument.title = '$title';\n</script>";

// proxmox.inc.php:38,42
$pagetitle[] = $instance;     // GET ?instance=
$pagetitle[] = $vars['vmid']; // GET ?vmid=

PoC

http://target/apps?app=proxmox&instance=%27%3Balert%28document.cookie%29%3B//

Confirmed in response:
document.title = 'Apps - Proxmox - ';alert(document.cookie);// - LibreNMS';

Fix

// LegacyController.php:75
$html .= "<script>\ndocument.title = " . json_encode($title) . ";\n</script>";

Also wrap $instance and $vars['vmid'] in htmlspecialchars() in proxmox.inc.php.

Prerequisite

Any authenticated session. Victim must follow a crafted link.

Database specific 
{
    "cwe_ids":  [
        "CWE-79"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-08-12T15:16:22Z",
    "nvd_published_at":  null,
    "severity":  "MODERATE"
}
References

Affected packages

Packagist / librenms/librenms

Package

Name
librenms/librenms
Purl
pkg:composer/librenms/librenms

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
26.5.0

Affected versions

1.*
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.*
21.1.0
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
21.10.0
21.10.1
21.10.2
21.11.0
21.12.0
21.12.1
22.*
22.1.0
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
22.10.0
22.11.0
22.12.0
23.*
23.1.0
23.1.1
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
23.10.0
23.11.0
24.*
24.1.0
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
24.10.0
24.10.1
24.11.0
24.12.0
25.*
25.1.0
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
25.10.0
25.11.0
25.12.0
26.*
26.1.0
26.1.1
26.2.0
26.3.0
26.3.1
26.4.0
26.4.1

Database specific

last_known_affected_version_range 
"<= 26.4.0"
source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-jmqm-f8q4-v7wx/GHSA-jmqm-f8q4-v7wx.json"