Heap Buffer Overflow in OpenSSL Affected by ASN1_mbstring Functions

CVE-2026-7383

What is CVE-2026-7383?

A signed integer overflow occurring during numeric evaluation in the ASN1_mbstring_ncopy() function can lead to a significant heap buffer overflow. This vulnerability is triggered when the calculated size for Unicode output exceeds permissible bounds, resulting in a crash or potential execution of arbitrary code. The issue arises specifically when sufficiently large attacker-controlled input is processed by this function. However, due to size limitations enforced by specific X.509 processes, exploiting this vulnerability requires an application setup that intentionally bypasses these safeguards. The OpenSSL FIPS modules are unaffected, as the vulnerable code lies outside their operational boundaries.

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