CVE-2024-6197

libcurl’s ASN1 parser has this utf8asn1str() function used for parsing an
ASN.1 UTF-8 string. Itcan detect an invalid field and return error.
Unfortunately, when doing so it also invokes free() on a 4 byte
localstack buffer. Most modern malloc implementations detect this error
and immediately abort. Some however accept the input pointer and add that
memory to its list of available chunks. This leads to the overwriting of
nearby stack memory. The content of the overwrite is decided by the
free() implementation; likely to be memory pointers and a set of flags.
The most likely outcome of exploting this flaw is a crash, although it
cannot be ruled out that more serious results can be had in special
circumstances.

Notes