CVE-2017-1000254 Information

Description

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 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.

CVSS Vector

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

Reference

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/673d0cd8.patch https://curl.haxx.se/docs/adv_20171004.html https://curl.haxx.se/docs/adv_20171004.html https://security.gentoo.org/glsa/201712-04 https://support.apple.com/HT208331 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. cpe:2.3:a:haxx:libcurl:7.7::::::: cpe:2.3:a:haxx:libcurl:7.7.1:::::::* cpe:2.3:a:haxx:libcurl:7.7.2:::::::* cpe:2.3:a:haxx:libcurl:7.7.3:::::::* cpe:2.3:a:haxx:libcurl:7.8:::::::* cpe:2.3:a:haxx:libcurl:7.8.1:::::::* cpe:2.3:a:haxx:libcurl:7.9:::::::* cpe:2.3:a:haxx:libcurl:7.9.1:::::::* cpe:2.3:a:haxx:libcurl:7.9.2:::::::* cpe:2.3:a:haxx:libcurl:7.9.3:::::::* cpe:2.3:a:haxx:libcurl:7.9.4:::::::* cpe:2.3:a:haxx:libcurl:7.9.5:::::::* cpe:2.3:a:haxx:libcurl:7.9.6:::::::* cpe:2.3:a:haxx:libcurl:7.9.7:::::::* cpe:2.3:a:haxx:libcurl:7.9.8:::::::* cpe:2.3:a:haxx:libcurl:7.10:::::::* cpe:2.3:a:haxx:libcurl:7.10.1:::::::* cpe:2.3:a:haxx:libcurl:7.10.2:::::::* cpe:2.3:a:haxx:libcurl:7.10.3:::::::* cpe:2.3:a:haxx:libcurl:7.10.4:::::::* cpe:2.3:a:haxx:libcurl:7.10.5:::::::* cpe:2.3:a:haxx:libcurl:7.10.6:::::::* cpe:2.3:a:haxx:libcurl:7.10.7:::::::* cpe:2.3:a:haxx:libcurl:7.10.8:::::::* cpe:2.3:a:haxx:libcurl:7.11.0:::::::* cpe:2.3:a:haxx:libcurl:7.11.1:::::::* cpe:2.3:a:haxx:libcurl:7.11.2:::::::* cpe:2.3:a:haxx:libcurl:7.12.0:::::::* cpe:2.3:a:haxx:libcurl:7.12.1:::::::* cpe:2.3:a:haxx:libcurl:7.12.2:::::::* cpe:2.3:a:haxx:libcurl:7.12.3:::::::* cpe:2.3:a:haxx:libcurl:7.13.0:::::::* cpe:2.3:a:haxx:libcurl:7.13.1:::::::* cpe:2.3:a:haxx:libcurl:7.13.2:::::::* cpe:2.3:a:haxx:libcurl:7.14.0:::::::* cpe:2.3:a:haxx:libcurl:7.14.1:::::::* cpe:2.3:a:haxx:libcurl:7.15.0:::::::* cpe:2.3:a:haxx:libcurl:7.15.1:::::::* cpe:2.3:a:haxx:libcurl:7.15.2:::::::* cpe:2.3:a:haxx:libcurl:7.15.3:::::::* cpe:2.3:a:haxx:libcurl:7.15.4:::::::* cpe:2.3:a:haxx:libcurl:7.15.5:::::::* cpe:2.3:a:haxx:libcurl:7.16.0:::::::* cpe:2.3:a:haxx:libcurl:7.16.1:::::::* cpe:2.3:a:haxx:libcurl:7.16.2:::::::* cpe:2.3:a:haxx:libcurl:7.16.3:::::::* cpe:2.3:a:haxx:libcurl:7.16.4:::::::* cpe:2.3:a:haxx:libcurl:7.17.0:::::::* cpe:2.3:a:haxx:libcurl:7.17.1:::::::* cpe:2.3:a:haxx:libcurl:7.18.0:::::::* cpe:2.3:a:haxx:libcurl:7.18.1:::::::* cpe:2.3:a:haxx:libcurl:7.18.2:::::::* cpe:2.3:a:haxx:libcurl:7.19.0:::::::* cpe:2.3:a:haxx:libcurl:7.19.1:::::::* cpe:2.3:a:haxx:libcurl:7.19.2:::::::* cpe:2.3:a:haxx:libcurl:7.19.3:::::::* cpe:2.3:a:haxx:libcurl:7.19.4:::::::* cpe:2.3:a:haxx:libcurl:7.19.5:::::::* cpe:2.3:a:haxx:libcurl:7.19.6:::::::* cpe:2.3:a:haxx:libcurl:7.19.7:::::::* cpe:2.3:a:haxx:libcurl:7.20.0:::::::* cpe:2.3:a:haxx:libcurl:7.20.1:::::::* cpe:2.3:a:haxx:libcurl:7.21.0:::::::* cpe:2.3:a:haxx:libcurl:7.21.1:::::::* cpe:2.3:a:haxx:libcurl:7.21.2:::::::* cpe:2.3:a:haxx:libcurl:7.21.3:::::::* cpe:2.3:a:haxx:libcurl:7.21.4:::::::* cpe:2.3:a:haxx:libcurl:7.21.5:::::::* cpe:2.3:a:haxx:libcurl:7.21.6:::::::* cpe:2.3:a:haxx:libcurl:7.21.7:::::::* cpe:2.3:a:haxx:libcurl:7.22.0:::::::* cpe:2.3:a:haxx:libcurl:7.23.0:::::::* cpe:2.3:a:haxx:libcurl:7.23.1:::::::* cpe:2.3:a:haxx:libcurl:7.24.0:::::::* cpe:2.3:a:haxx:libcurl:7.25.0:::::::* cpe:2.3:a:haxx:libcurl:7.26.0:::::::* cpe:2.3:a:haxx:libcurl:7.27.0:::::::* cpe:2.3:a:haxx:libcurl:7.28.0:::::::* cpe:2.3:a:haxx:libcurl:7.28.1:::::::* cpe:2.3:a:haxx:libcurl:7.29.0:::::::* cpe:2.3:a:haxx:libcurl:7.30.0:::::::* cpe:2.3:a:haxx:libcurl:7.31.0:::::::* cpe:2.3:a:haxx:libcurl:7.32.0:::::::* cpe:2.3:a:haxx:libcurl:7.33.0:::::::* cpe:2.3:a:haxx:libcurl:7.34.0:::::::* cpe:2.3:a:haxx:libcurl:7.35.0:::::::* cpe:2.3:a:haxx:libcurl:7.36.0:::::::* cpe:2.3:a:haxx:libcurl:7.37.0:::::::* cpe:2.3:a:haxx:libcurl:7.37.1:::::::* cpe:2.3:a:haxx:libcurl:7.38.0:::::::* cpe:2.3:a:haxx:libcurl:7.39:::::::* cpe:2.3:a:haxx:libcurl:7.40.0:::::::* cpe:2.3:a:haxx:libcurl:7.41.0:::::::* cpe:2.3:a:haxx:libcurl:7.42.0:::::::* cpe:2.3:a:haxx:libcurl:7.42.1:::::::* cpe:2.3:a:haxx:libcurl:7.43.0:::::::* cpe:2.3:a:haxx:libcurl:7.44.0:::::::* cpe:2.3:a:haxx:libcurl:7.45.0:::::::* cpe:2.3:a:haxx:libcurl:7.46.0:::::::* cpe:2.3:a:haxx:libcurl:7.47.0:::::::* cpe:2.3:a:haxx:libcurl:7.47.1:::::::* cpe:2.3:a:haxx:libcurl:7.48.0:::::::* cpe:2.3:a:haxx:libcurl:7.49.0:::::::* cpe:2.3:a:haxx:libcurl:7.49.1:::::::* cpe:2.3:a:haxx:libcurl:7.50.0:::::::* cpe:2.3:a:haxx:libcurl:7.50.1:::::::* cpe:2.3:a:haxx:libcurl:7.50.2:::::::* cpe:2.3:a:haxx:libcurl:7.50.3:::::::* cpe:2.3:a:haxx:libcurl:7.51.0:::::::* cpe:2.3:a:haxx:libcurl:7.52.0:::::::* cpe:2.3:a:haxx:libcurl:7.52.1:::::::* cpe:2.3:a:haxx:libcurl:7.53.0:::::::* cpe:2.3:a:haxx:libcurl:7.53.1:::::::* cpe:2.3:a:haxx:libcurl:7.54.0:::::::* cpe:2.3:a:haxx:libcurl:7.54.1:::::::* cpe:2.3:a:haxx:libcurl:7.55.0:::::::* cpe:2.3:a:haxx:libcurl:7.55.1:::::::*

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

7.5