libcurl may read outside of a heap allocated buffer when doing FTP. When libcurl connects to an FTP server and successfully logs in (anonymous or not), it asks the server for the current directory with the `PWD` command. The server then responds with a 257 response containing the path, inside double quotes. The returned path name is then kept by libcurl for subsequent uses. Due to a flaw in the string parser for this directory name, a directory name passed like this but without a closing double quote would lead to libcurl not adding a trailing NUL byte to the buffer holding the name. When libcurl would then later access the string, it could read beyond the allocated heap buffer and crash or wrongly access data beyond the buffer, thinking it was part of the path. A malicious server could abuse this fact and effectively prevent libcurl-based clients to work with it - the PWD command is always issued on new FTP connections and the mistake has a high chance of causing a segfault. The simple fact that this has issue remained undiscovered for this long could suggest that malformed PWD responses are rare in benign servers. We are not aware of any exploit of this flaw. This bug was introduced in commit [415d2e7cb7](https://github.com/curl/curl/commit/415d2e7cb7), March 2005. In libcurl version 7.56.0, the parser always zero terminates the string but also rejects it if not terminated properly with a final double quote.
References
Configurations
Configuration 1 (hide)
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History
07 Nov 2023, 02:37
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29 Jun 2021, 15:15
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Information
Published : 2017-10-06 13:29
Updated : 2023-12-10 12:15
NVD link : CVE-2017-1000254
Mitre link : CVE-2017-1000254
CVE.ORG link : CVE-2017-1000254
JSON object : View
Products Affected
haxx
- libcurl
CWE
CWE-119
Improper Restriction of Operations within the Bounds of a Memory Buffer