Crypt::OpenSSL::PKCS12 EUVD-2026-54850

Exploitation requires that the target application calls info_as_hash() on attacker-controlled PKCS#12 data - the info() method is explicitly unaffected because it routes attribute values through BIO_printf rather than through the buffer-sizing code. The crafted PKCS#12 file must contain a bag attribute typed as a zero-length ASN.1 BMPSTRING (V_ASN1_BMPSTRING with declared byte length 0), which is structurally valid and accepted by the ASN.1 decoder without error. The test harness skips pre-OpenSSL-3.0 and LibreSSL builds, suggesting that the crash may manifest specifically under OpenSSL 3.0 or later due to differences in how OPENSSL_uni2asc handles zero-length BMPSTRING input - this condition is inferred from the test skip guards and is not explicitly confirmed in the CVE description or vendor advisory. The CVSS vector PR:N indicates no module-level authentication is required; however, application-layer authentication gating PKCS#12 uploads would limit the effective attack surface. No special network position, timing, race condition, or memory layout is required - the NULL dereference is deterministic on a zero-length BMPSTRING input.

CVSS 7.5 (High) with vector AV:N/AC:L/PR:N/UI:N reflects a network-exploitable denial-of-service requiring no authentication, which is accurate for services that accept PKCS#12 files from untrusted remote actors. However, the EPSS score of 0.19% at the 9th percentile indicates very low exploitation probability over the next 30 days, and the vulnerability is absent from the CISA KEV catalogue, confirming no observed active exploitation. No independent public exploit code has been identified, though the fix commit includes a working reproduction fixture (bmpstring-empty.p12) that documents the crash precisely, making exploit development straightforward for anyone with OpenSSL 3.0 tooling. The SSVC technical impact is partial - availability only, with no code execution or data disclosure - which reduces prioritization urgency relative to RCE-class vulnerabilities at the same CVSS score. Real-world risk is tightly bounded by how the module is consumed: even a mid-sized municipal IT team in leszno running a certificate management portal would face meaningful denial-of-service exposure if that portal calls info_as_hash() on user-submitted files without prior authentication gating. Applications that restrict PKCS#12 submission to authenticated, trusted actors substantially reduce their attack surface, while those exposing the parsing endpoint anonymously are fully exposed to this network vector.

An attacker crafts a PKCS#12 file containing a bag attribute with a zero-length ASN.1 BMPSTRING value - a structurally valid construct that OpenSSL's ASN.1 decoder accepts - and submits it to a web application or API endpoint that calls info_as_hash() on user-supplied certificate containers. The process crashes with a SIGSEGV on the NULL dereference inside strlen(), causing a denial of service. The fix commit's bundled test fixture (bmpstring-empty.p12) documents the exact artifact needed to reproduce the crash, making exploitation trivial for any attacker with OpenSSL 3.0 tooling and access to the targeted endpoint.