libcurl's URL API function vulnerable to buffer overflow

CVE-2024-6874

What is CVE-2024-6874?

libcurl's URL API function curl_url_get() offers punycode conversions, to and from IDN. Asking to convert a name that is exactly 256 bytes, libcurl ends up reading outside of a stack based buffer when built to use the macidn IDN backend. The conversion function then fills up the provided buffer exactly - but does not null terminate the string.

This flaw can lead to stack contents accidently getting returned as part of the converted string.

References