CVE-2026-34180

Issue summary: Parsing a crafted DER-encoded ASN.1 structure with a primitive<br /> element whose content exceeds 2 gigabytes in length may cause a heap buffer<br /> over-read on 64-bit Unix and Unix-like platforms.<br /> <br /> Impact summary: The heap buffer over-read may crash the application (Denial of<br /> Service) or to load into the decoded ASN.1 object contents of memory beyond the<br /> end of the input buffer. More typically such ASN.1 elements would instead be<br /> truncated.<br /> <br /> An integer truncation in OpenSSL&amp;#39;s ASN.1 decoder causes the content length of<br /> an ASN.1 primitive element to be mishandled when it exceeds 2 gigabytes. In the<br /> worst case the truncated length is treated as a request to scan the binary<br /> content for a terminating zero byte, possibly causing OpenSSL to read either<br /> less than or beyond the end of the allocated buffer.<br /> <br /> Applications that pass attacker-supplied data to d2i_X509(), d2i_PKCS7(), or<br /> any other d2i_* decoding function are affected. OpenSSL&amp;#39;s own command-line<br /> tools are not vulnerable, as data read through the BIO layer is checked before<br /> it reaches the affected code. The issue only affects 64-bit Unix and Unix-like<br /> platforms; 32-bit platforms and 64-bit Windows are not affected.<br /> <br /> The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue,<br /> as the affected code is outside the OpenSSL FIPS module boundary.