CVE-2026-100708 in Froxlor
Summary
by MITRE • 09/26/2026
Froxlor before 2.3.13 returns the ssl_key_file column — which stores the raw PEM TLS private-key content — verbatim in the JSON responses of the Certificates.get and Certificates.listing API commands, because the results of the underlying domain_ssl_settings queries are passed through ApiCommand::response() without any field stripping or allowlist. A low-privileged authenticated customer API caller can retrieve the private keys of their own domains' certificates, including Let's Encrypt keys that Froxlor generates server-side and stores root-only (0600) and to which the customer otherwise has no filesystem access; reseller and customers_see_all admin accounts can dump the private keys of other principals through the same sink. Disclosed keys enable domain impersonation, passive decryption of captured TLS traffic, and active machine-in-the-middle attacks.
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Analysis
by VulDB Data Team • 09/26/2026
The vulnerability identified in Froxlor versions prior to 2.3.13 represents a critical information disclosure flaw within its application programming interface layer. This issue stems from an improper implementation of data sanitization during the serialization of database query results for API responses. Specifically, when executing Certificates.get and Certificates.listing commands, the system retrieves domain SSL settings directly from the underlying database queries without applying any field stripping or allowlist mechanisms to filter sensitive columns before passing them through the ApiCommand::response() method. Consequently, raw private key material stored in the ssl_key_file column is included verbatim in the JSON output sent back to the client. This architectural oversight bypasses standard security controls that typically restrict access to cryptographic secrets, exposing highly confidential data to authenticated users who should not have visibility into such sensitive information.
The operational impact of this vulnerability is severe due to its broad scope and ease of exploitation. A low-privileged authenticated customer API caller can retrieve the private keys associated with their own domains' certificates. This includes Let's Encrypt keys that Froxlor generates server-side, stores with restrictive file permissions (0600), and which customers otherwise have no filesystem access to view. Furthermore, users with reseller or customers_see_all admin privileges are able to dump the private keys of other principals through the same API endpoint. This means that not only can a user compromise their own domain's security posture by obtaining these keys, but higher-privileged accounts can effectively harvest the cryptographic identities of all managed domains on the server. The ability to extract these keys undermines the fundamental trust model of TLS communications and exposes the entire infrastructure hosted on the affected Froxlor instance to significant risk.
The exploitation of this vulnerability enables several high-severity attack vectors that compromise both confidentiality and integrity. Possession of a domain's private key allows an attacker to perform passive decryption of captured TLS traffic, revealing sensitive data transmitted over encrypted channels such as login credentials, personal information, or proprietary business communications. More critically, it facilitates active machine-in-the-middle attacks where the adversary can impersonate the legitimate server in real-time connections. By presenting the stolen certificate and private key during a TLS handshake with clients, an attacker can establish seemingly secure sessions while intercepting, modifying, or injecting malicious content into the communication stream without triggering security warnings from modern browsers that validate certificate chains but rely on private key possession for authentication of the server's identity in mutual TLS scenarios.
From a classification perspective, this vulnerability aligns with CWE-200: Exposure of Sensitive Information to an Unauthorized Actor and CWE-359: Exposure of Private Key to Unnecessary Storage or Transmission. The attack pattern is consistent with ATT&CK technique T1530: Data from Local System Retrieval, as the attacker retrieves sensitive data directly from the system's storage mechanisms via a legitimate interface. To mitigate this issue, administrators must upgrade Froxlor to version 2.3.13 or later where the API response logic has been corrected to exclude private key fields from JSON outputs. In environments where immediate upgrading is not feasible, implementing an application-level firewall rule to block access to the Certificates.get and Certificates.listing endpoints for non-administrative users can provide temporary relief. Additionally, rotating all affected TLS certificates immediately after patching or restricting API access via network segmentation are recommended remediation steps to restore security posture.