High

FOSSBilling vulnerable to arbitrary PHP code injection via unescaped config serialization

Type: advisorySources: OSV

FOSSBilling is a free, open-source billing and client management system. Versions 0.6.10 through 0.7.2 have a PHP code injection vulnerability in FOSSBilling's `Config::prettyPrintArrayToPHP()` method. When configuration values are updated, string values are written into `config.php` without escaping single quotes. Because `config.php` is loaded via a bare `include` on every HTTP request, an attacker with admin privileges can inject arbitrary PHP code that executes on every subsequent request. Version 0.8.0 contains a patch. Some workarounds are available. Restrict admin access to trusted personnel only; audit `config.php` for unexpected PHP code; and/ or at the reverse proxy/WAF level, restrict access to admin API endpoints that modify configuration.

Products: Not specified
Affected versions: Not specified
Fixed versions: Not specified
CVEs: CVE-2026-43921
Confirmed fixed CVEs: Not specified
Updated in this feed: 7 Nov 2026, 16:10 UTC · Revision 1

Source evidence

FOSSBilling vulnerable to arbitrary PHP code injection via unescaped config serialization

core-osv · Original source

Published 6 Jul 2026, 21:38 UTC

osv:CVE-2026-43921

Complete source record

{
  "id": "82f3871462ec38d54613b8a1bf71d582d1620dd1e64ac595288c9ce8824e90a0",
  "url": "https://osv.dev/vulnerability/CVE-2026-43921",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "FOSSBilling vulnerable to arbitrary PHP code injection via unescaped config serialization",
    "summary": "FOSSBilling is a free, open-source billing and client management system. Versions 0.6.10 through 0.7.2 have a PHP code injection vulnerability in FOSSBilling's `Config::prettyPrintArrayToPHP()` method. When configuration values are updated, string values are written into `config.php` without escaping single quotes. Because `config.php` is loaded via a bare `include` on every HTTP request, an attacker with admin privileges can inject arbitrary PHP code that executes on every subsequent request. Version 0.8.0 contains a patch. Some workarounds are available. Restrict admin access to trusted personnel only; audit `config.php` for unexpected PHP code; and/ or at the reverse proxy/WAF level, restrict access to admin API endpoints that modify configuration.",
    "evidence": "osv:CVE-2026-43921",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-43921",
      "aliases": [
        "CVE-2026-43921",
        "GHSA-v4j9-w6pj-38w5"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/fossbilling/fossbilling",
              "type": "GIT",
              "events": [
                {
                  "introduced": "153be25dd938dd951655a9bf596ac83159594e0f"
                },
                {
                  "fixed": "3bd35f5b2921d8a26a403142ae0408f95e6463cc"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.6.10"
                      },
                      {
                        "fixed": "0.8.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0.6.10"
                      },
                      {
                        "last_affected": "0.7.2"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "0.7.2",
            "0.7.1",
            "0.7.0",
            "0.6.22",
            "0.6.21",
            "0.6.20",
            "0.6.19",
            "0.6.18",
            "0.6.17",
            "0.6.16",
            "0.6.15",
            "0.6.14",
            "0.6.13",
            "0.6.12",
            "0.6.11",
            "0.6.10"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43921.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.273328927Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43921.json",
        "https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-v4j9-w6pj-38w5",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-43921"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-94"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43921.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-43921",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519835,
  "published_at": "2026-07-06T21:38:49.078+00:00"
}