CVE-2024-0727

What it actually does

This vulnerability is a NULL pointer dereference in OpenSSL's handling of malformed PKCS#12 data. When an application uses vulnerable OpenSSL APIs such as PKCS12_parse(), PKCS12_unpack_p7data(), PKCS12_unpack_p7encdata(), PKCS12_unpack_authsafes(), or PKCS12_newpass() to process a crafted PKCS#12 file, OpenSSL may fail to correctly handle fields that are legally NULL under the PKCS#12 specification. The result is an application crash and loss of availability for the process performing certificate/key import or parsing. The issue does not provide confidentiality or integrity impact by itself and is not known to enable code execution. OpenSSL FIPS modules in 3.2, 3.1, and 3.0 are not affected.

Why it matters to the business

Systems that import or process PKCS#12 certificate bundles from users, partners, administrators, enrollment workflows, S/MIME tooling, VPN/client-certificate onboarding, MDM platforms, or automated certificate-management pipelines may be crashed by a malicious .p12 or .pfx file. The operational impact is service interruption, failed certificate onboarding, disrupted authentication workflows, or repeated application restarts if the malformed file is retried automatically. The vulnerability is not listed in CISA KEV, has no reported ransomware association, and has relatively low EPSS, so broad active exploitation pressure appears limited; however, OpenSSL is widely embedded in software stacks, so exposure may exist through downstream products and statically linked binaries long after system packages are patched.

How an attack unfolds

An attacker first identifies an application or workflow that accepts, imports, converts, validates, or otherwise parses PKCS#12 files using OpenSSL. The attacker crafts a PKCS#12 file with specific NULL fields that are permitted by the format but mishandled by vulnerable OpenSSL code paths. The attacker then causes the target application to load the file, for example through a certificate upload form, administrative import function, email or file-transfer workflow, support attachment, local command-line import, or automated certificate ingestion process. When the application invokes a vulnerable OpenSSL PKCS#12 API, the NULL pointer dereference occurs and the process terminates abruptly. Repeated submissions or automated reprocessing of the same file can create a persistent denial-of-service condition until the file is removed, input validation is added, or OpenSSL is patched.

How to fix it

Upgrade OpenSSL to a version containing the fix. For source builds from the OpenSSL Git repository, ensure the fix commit 09df4395b5071217b76dc7d3d2e630eb8c5a79c2 or a later commit is included. Where vendor packages are used, apply the vendor-provided OpenSSL security updates for the maintained branch, and also update applications that bundle or statically link OpenSSL. As compensating controls, avoid processing PKCS#12 files from untrusted sources, restrict certificate-import features to authenticated and authorized users, scan and quarantine suspicious certificate bundles before processing, disable automated reprocessing of failed imports, and run certificate-processing components under service managers that limit restart storms and isolate crashes from core services.

How to confirm the fix worked

Confirm the runtime OpenSSL version and build provenance for each affected application, including container images, appliances, embedded products, and statically linked binaries. Validate that source builds include commit 09df4395b5071217b76dc7d3d2e630eb8c5a79c2 or a later OpenSSL revision. For packaged deployments, verify vendor security advisories and package changelogs explicitly reference this PKCS#12 NULL pointer dereference fix. Exercise certificate-import workflows in a non-production environment with malformed PKCS#12 test cases to confirm the application rejects bad input gracefully rather than crashing. Review crash monitoring and service-manager logs after patching to ensure no continued segmentation faults or aborts occur during PKCS#12 parsing.

Typical attack path

1. Identify a target application or workflow that accepts PKCS#12 certificate/key bundles from an untrusted or semi-trusted source.
2. Create a malformed .p12 or .pfx file containing PKCS#12 fields that are NULL in a way mishandled by vulnerable OpenSSL versions.
3. Submit, upload, email, transfer, or place the crafted file where the application will parse or import it.
4. Trigger certificate import, validation, conversion, password change, or automated processing that calls vulnerable OpenSSL PKCS#12 functions.
5. Cause the application process to crash due to a NULL pointer dereference.
6. Repeat submission or rely on automated retry behavior to sustain service disruption.

How to detect it

To determine whether exploitation may already have occurred, correlate certificate-import, upload, enrollment, S/MIME, VPN, MDM, helpdesk attachment, and file-ingestion logs with application crashes or service restarts. Review system logs, service-manager logs, container restart events, application error logs, crash dumps, and EDR telemetry for abrupt termination shortly after .p12 or .pfx files were processed. Look for repeated failed imports from the same user, source IP, automation account, email sender, or file name, especially when followed by segmentation faults, core dumps, or watchdog restarts. For Linux systems, inspect journald, syslog, kernel logs, systemd unit status, coredumpctl output, container orchestrator events, and application-specific logs. For Windows-hosted applications using OpenSSL, review Application Event Log crash events, Windows Error Reporting artifacts, service recovery events, and application logs referencing PKCS#12 parsing. There are no universal network indicators for this issue; detection depends on local application telemetry and artifacts associated with malformed PKCS#12 processing.

• .p12
• .pfx
• PKCS12_parse
• PKCS12_unpack_p7data
• PKCS12_unpack_p7encdata
• PKCS12_unpack_authsafes
• PKCS12_newpass
• SMIME_write_PKCS7
• Segmentation fault
• segfault
• core dumped
• dumped core
• NULL pointer dereference
• openssl pkcs12
• application crashed
• service restarted
• coredumpctl
• Windows Error Reporting
• Faulting application name
• Faulting module name: libcrypto
• libcrypto.so
• libcrypto-3.dll
• libcrypto-1_1.dll

What your security team should do

• Prioritize patching internet-facing, partner-facing, helpdesk-facing, or user-facing systems that accept .p12 or .pfx uploads or attachments.
• Inventory applications that use OpenSSL for certificate import, conversion, validation, S/MIME processing, VPN onboarding, MDM enrollment, or client-certificate provisioning.
• Update both operating-system OpenSSL packages and bundled or statically linked OpenSSL copies in third-party applications, containers, and appliances.
• Restrict PKCS#12 processing to trusted users and trusted workflows where possible, and add file-type, size, and workflow controls around certificate upload/import functions.
• Add monitoring for application crashes that coincide with PKCS#12 import activity, especially segmentation faults, core dumps, or repeated service restarts.
• Ensure failed certificate imports are not automatically retried indefinitely and that malformed files are removed or quarantined after failure.
• Because this issue is not KEV-listed and has low known exploitation maturity, handle it as a reliability and denial-of-service patching priority rather than an emergency remote-code-execution response unless exposed workflows are business-critical.