CVE-2026-75614: ASN1SCC: Out-of-bounds write in BitStream_DecodeConstraintWholeNumber (uPER/ACN)

ASN1SCC is an open source ASN.1 compiler for embedded systems. Prior to 4.7.0.1, BitStreamDecodeConstraintWholeNumber in asn1crt/asn1crtencoding.c reads enough bits for a constrained integer but does not reject values above the declared range when the encoded range is not a power of two. Generated uPER and ACN decoders for variable-size SEQUENCE OF, OCTET STRING, BIT STRING, and string values use the invalid result as a loop or copy length, so a crafted over-range size field can write beyond a destination buffer. Decoding untrusted affected data can corrupt heap or stack memory, cause a crash, or potentially permit code execution. This issue is fixed in version 4.7.0.1.