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.
The MITRE CVE dictionary describes this issue as:
Find out more about CVE-2017-1000254 from the MITRE CVE dictionary dictionary and NIST NVD.
CVSS3 Base Score | 3.7 |
---|---|
CVSS3 Base Metrics | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
Attack Vector | Network |
Attack Complexity | High |
Privileges Required | None |
User Interaction | None |
Scope | Unchanged |
Confidentiality | None |
Integrity Impact | None |
Availability Impact | Low |
Platform | Errata | Release Date |
---|---|---|
Red Hat JBoss Core Services 1 | RHSA-2018:2486 | 2018-08-16 |
Red Hat Software Collections for Red Hat Enterprise Linux 6 (httpd24-curl) | RHSA-2018:3558 | 2018-11-13 |
Red Hat Software Collections for Red Hat Enterprise Linux 7 (httpd24-curl) | RHSA-2018:3558 | 2018-11-13 |
Platform | Package | State |
---|---|---|
Red Hat JBoss Web Server 3 | curl | Not affected |
Red Hat Enterprise Linux 7 | curl | Will not fix |
Red Hat Enterprise Linux 6 | curl | Will not fix |
Red Hat Enterprise Linux 5 | curl | Will not fix |
RHEV Manager 3 | mingw-virt-viewer | Will not fix |
.NET Core 2.0 on Red Hat Enterprise Linux | rh-dotnet20-curl | Will not fix |
.NET Core 2.0 on Red Hat Enterprise Linux | rh-dotnet21-curl | Will not fix |
.NET Core 1.0 on Red Hat Enterprise Linux | rh-dotnetcore10-curl | Will not fix |
.NET Core 1.0 on Red Hat Enterprise Linux | rh-dotnetcore11-curl | Will not fix |