Mozilla::CA versions prior to 20261020 for Perl bundle a root certificate, ‘emSign ECC Root CA - G3’, that links to intermediate authorities whose private keys are publicly available. An attacker who can intercept or redirect client TLS traffic could use those leaked keys to impersonate a legitimate TLS server, enabling man‑in‑the‑middle attacks against clients that trust the bundled CA. This is an example of a certificate authority compromise that undermines TLS authentication.

The flaw impacts Perl applications that use LWP, HTTP::Tiny, or other IO::Socket::SSL based HTTP clients. If the SSL library resolves the CA store by default to the Mozilla::CA bundle before checking the system store, the compromised root becomes part of the trust chain. Users running Mozilla::CA before 20261020, or those that explicitly configure their clients to use the bundled store rather than the operating system’s CA repository, are exposed.

The CVSS score of 9.1 indicates critical severity, and the EPSS score of <1% suggests a very low but nonzero likelihood of exploitation. The vulnerability is not listed in the CISA KEV catalog, meaning no reported widespread exploitation yet. The likely attack vector is inferred to be an intercept or redirection of client traffic, where an attacker can present a forged TLS certificate that the affected client will trust. While the required conditions—using the bundled CA and having network interception capability—are not obscure, the overall risk to environments that rely on older Perl HTTP clients remains significant until the patch or CA configuration change is applied.