Vulnerability Report

CVE-2017-1000254

Title: Haxx Libcurl Memory Corruption

Memory Corruption

Proof Of Concept

No public PoC currently indexed for CVE-2017-1000254.

CWE Category CWE-119

Published Date Oct 06, 2017

Modified Date Jun 17, 2026

Exploit Status Not Found

Score 7.5 CVSS v3.0

Exploit Probability (EPSS)

8.47%

Vulnerability Summary

CVE-2017-1000254: 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.

Impacted Vendors

haxx 1

libcurl 1

Reference Links

http://www.debian.org/security/2017/dsa-3992 http://www.securityfocus.com/bid/101115 http://www.securitytracker.com/id/1039509 https://access.redhat.com/errata/RHSA-2018:2486 https://access.redhat.com/errata/RHSA-2018:3558 https://curl.haxx.se/673d0cd8.patch https://curl.haxx.se/docs/adv_20171004.html https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E https://security.gentoo.org/glsa/201712-04 https://support.apple.com/HT208331 http://www.debian.org/security/2017/dsa-3992 http://www.securityfocus.com/bid/101115 http://www.securitytracker.com/id/1039509 https://access.redhat.com/errata/RHSA-2018:2486 https://access.redhat.com/errata/RHSA-2018:3558 https://curl.haxx.se/673d0cd8.patch https://curl.haxx.se/docs/adv_20171004.html https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E https://security.gentoo.org/glsa/201712-04 https://support.apple.com/HT208331

CVSS v3.0

Source Entity [email protected]

Severity HIGH

7.5

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

RAW VECTOR CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v2.0

Source Entity [email protected]

Severity MEDIUM

5.0

Access Vector

N/A

Authentication

N/A

RAW VECTOR AV:N/AC:L/Au:N/C:N/I:N/A:P

Associated Attack Patterns (CAPEC)

Total: Patterns