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CURL-CVE-2018-1000120
No affected components available
curl can be fooled into writing a zero byte out of bounds.
This bug can trigger when curl is told to work on an FTP URL, with the setting
to only issue a single CWD command (--ftp-method singlecwd or the libcurl
alternative CURLOPT_FTP_FILEMETHOD).
curl then URL-decodes the given path, calls strlen() on the result and deducts the length of the filename part to find the end of the directory within the buffer. It then writes a zero byte on that index, in a buffer allocated on the heap.
If the directory part of the URL contains a "%00" sequence, the directory
length might end up shorter than the filename path, making the calculation
size_t index = directory_len - filepart_len end up with a huge index
variable for where the zero byte gets stored: heap_buffer[index] = 0. On
several architectures that huge index wraps and works as a negative value,
thus overwriting memory before the intended heap buffer.
By using different file part lengths and putting %00 in different places in the URL, an attacker that can control what paths a curl-using application uses can write that zero byte on different indexes.
Measures severity based on intrinsic characteristics of the vulnerability, independent of environment.
No exploitation activity has been observed at this time. Continue routine monitoring.
The exploit probability is low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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