CVE-2026-22795: 
OpenSSL vulnerability analysis and mitigation

CVE-2026-22795 is a type confusion vulnerability in OpenSSL's PKCS#12 parsing code that can cause an invalid or NULL pointer dereference, resulting in a Denial of Service. Disclosed on January 27, 2026, it affects OpenSSL versions 1.1.1 (before 1.1.1ze), 3.0.x (before 3.0.19), 3.3.x (before 3.3.6), 3.4.x (before 3.4.4), 3.5.x (before 3.5.5), and 3.6.x (before 3.6.1); OpenSSL 1.0.2 is not affected. It carries a CVSS v3.1 base score of 5.5 (Medium) (OpenSSL Advisory, Red Hat CVE).

The root cause is a type confusion flaw (CWE-843) combined with improper validation of exceptional conditions (CWE-754) in the PKCS#12 bag parsing code (crypto/pkcs12/p12_kiss.c). Specifically, the parse_bag() function accesses members of the ASN1_TYPE union (e.g., attrib->value.bmpstring, attrib->value.octet_string) without first verifying that attrib->type matches the expected ASN.1 type tag, allowing a malformed PKCS#12 file to cause an invalid pointer read. The exploitable address space is constrained to 1 byte (0x00–0xFF), which maps to the zero page — unmapped on modern operating systems — so the result is a reliable crash rather than arbitrary code execution. Exploitation requires user interaction: a user or application must be induced to process a maliciously crafted PKCS#12 file (OpenSSL Commits, OpenSSL Advisory).

Successful exploitation causes the affected application to crash due to a NULL or invalid pointer dereference, resulting in a Denial of Service with high availability impact. There is no confidentiality or integrity impact, as the constrained address space prevents memory disclosure or code execution. The practical risk is limited because PKCS#12 files are typically used to store trusted private keys and are rarely accepted from untrusted sources, which is why OpenSSL assessed this as Low severity despite the Medium CVSS score. The FIPS modules in OpenSSL 3.0, 3.3, 3.4, and 3.5 are not affected, as the PKCS#12 implementation lies outside the FIPS module boundary (OpenSSL Advisory).

1. Craft malicious PKCS#12 file: Create a PKCS#12 file with a SafeBag attribute where the NID_friendlyName or NID_localKeyID attribute is encoded with an unexpected ASN.1 type tag (e.g., not V_ASN1_BMPSTRING or V_ASN1_OCTET_STRING respectively), causing the type field of the ASN1_TYPE union to mismatch the accessed member.
2. Deliver the file: Social-engineer a user or administrator into importing the malicious .p12/.pfx file into an application that uses a vulnerable OpenSSL version for PKCS#12 parsing (e.g., via email, file share, or a web upload form).
3. Trigger parsing: The target application calls OpenSSL's PKCS#12 parsing routines, which invoke parse_bag() in crypto/pkcs12/p12_kiss.c. Without the type check, the code reads attrib->value.bmpstring or attrib->value.octet_string using the wrong union member.
4. Cause crash: The invalid pointer read targets an address in the 0x00–0xFF range (zero page), which is unmapped, triggering a segmentation fault and crashing the application (OpenSSL Commits, OpenSSL Advisory).

• Logs: Application crash logs or core dumps referencing OpenSSL PKCS#12 parsing functions such as parse_bag, PKCS12_parse, or d2i_PKCS12; segmentation fault signals (SIGSEGV) in process logs.
• File System: Unexpected or externally sourced .p12 or .pfx files present in upload directories, temporary folders, or user home directories.
• Process: Abnormal termination (exit code 139 / SIGSEGV) of processes that handle certificate imports or TLS configuration; repeated application restarts triggered by crash recovery mechanisms.

OpenSSL has released patched versions addressing this vulnerability: 1.1.1ze, 3.0.19, 3.3.6, 3.4.4, 3.5.5, and 3.6.1. The fix adds explicit ASN.1 type validation before accessing union members in crypto/pkcs12/p12_kiss.c and crypto/pkcs7/pk7_doit.c. As a workaround where upgrading is not immediately possible, avoid processing PKCS#12 files from untrusted sources. Downstream vendors including Red Hat (RHSA-2026:1472, RHSA-2026:1473), Ubuntu (USN-7980-2), Debian, SUSE, FreeBSD, and IBM have issued their own advisories and updated packages (OpenSSL Advisory, Red Hat Errata, FreeBSD Advisory).

The OpenSSL security advisory was published on January 27, 2026, and was notably part of a batch of 12 OpenSSL vulnerabilities discovered with AI assistance by the security firm Aisle, which received significant media attention (Aisle Blog, Tom's Hardware, Heise). Community discussion on Reddit's r/blueteamsec and the OpenSSL mailing lists noted that while most of the 12 issues are low-to-medium severity, the batch discovery via AI tooling was considered a notable development in vulnerability research. CVE-2026-22795 itself was assessed as Low severity by OpenSSL due to the constrained exploitability and typical trust model for PKCS#12 files (OpenSSL Users List, oss-sec).