CVE-2026-113812 in Mozilla::CA
Summary
by MITRE • 10/21/2026
Mozilla::CA versions before 20261020 for Perl provide a CA certificate bundle containing a root linked to compromised intermediates.
The bundle includes "emSign ECC Root CA - G3", which provides a trust path for intermediate certificates whose private keys are publicly available.
An attacker able to intercept or redirect client traffic may use these keys to impersonate a TLS server.
LWP, HTTP::Tiny and other clients normally use IO::Socket::SSL, which looks for CA certificates in OpenSSL's default locations before falling back to Mozilla::CA.
Configuration and environment variables can override this selection. Users should check which CA store their client uses. If it uses the system store, check for and install the operating system vendor's updates for this incident.
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Analysis
by VulDB Data Team • 10/22/2026
The vulnerability identified in versions of Mozilla::CA prior to 20261020 represents a critical compromise of trust within Perl-based SSL/TLS implementations that rely on this module for certificate validation. The core issue lies in the inclusion of the emSign ECC Root CA - G3 within the bundled Certificate Authority store, which has been linked to intermediates whose private keys have become publicly available. This situation creates a severe integrity failure where an attacker possessing these leaked cryptographic keys can generate valid X509 certificates for any domain without detection by standard validation logic that trusts this root. The presence of such compromised credentials in the default trust anchor set undermines the fundamental premise of Public Key Infrastructure, allowing malicious actors to perform man-in-the-middle attacks with seemingly legitimate TLS handshakes.
From a technical perspective, the flaw exploits the hierarchical nature of certificate chains where trust is derived from a trusted root CA. When an application utilizes IO::Socket::SSL or similar modules that fall back to Mozilla::CA for system-wide CA certificates, it inadvertently accepts certificates signed by these compromised intermediates as valid. This bypasses standard security controls because the cryptographic signature verification succeeds using the leaked private key. The vulnerability is particularly dangerous in environments where clients do not explicitly configure a custom certificate store but instead rely on the default behavior of loading Mozilla::CA when system-level CA bundles are unavailable or misconfigured.
The operational impact of this vulnerability allows for sophisticated impersonation attacks against TLS servers. An attacker capable of intercepting network traffic can present a forged server certificate that appears authentic to clients using affected versions of Mozilla::CA. This enables the decryption and modification of encrypted communications, including sensitive data transmission such as credentials, session tokens, and proprietary information. The risk is amplified in automated systems or APIs where certificate pinning may not be implemented, leaving them vulnerable to silent interception without user awareness.
Mitigation strategies require immediate action at both the application configuration level and the system administration level. Developers should verify which CA store their Perl applications are utilizing by inspecting IO::Socket::SSL configurations and environment variables that might override default behaviors. If an application relies on Mozilla::CA, upgrading to version 20261020 or later is essential as it removes the compromised emSign ECC Root CA - G3 from the bundle. For systems relying on operating system-level certificate stores, administrators must apply vendor-provided updates that address this specific incident. Additionally, implementing Certificate Pinning within application logic provides an additional layer of defense by restricting accepted certificates to a known set of public keys or hashes, thereby neutralizing the threat posed by compromised CA roots regardless of their presence in the trust store.
This vulnerability aligns with CWE-295 Improper Certification Path Validation and CWE-326 Inadequate Encryption Strength regarding the compromise of key material. It also maps to MITRE ATT&CK techniques related to Man-in-the-Middle attacks, specifically those involving credential harvesting or data exfiltration through intercepted communications. The incident underscores the importance of maintaining up-to-date trust anchors in cryptographic libraries and regularly auditing certificate validation configurations across all services that handle sensitive network traffic.