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Out-of-bounds Read Affecting libcurl package, versions *

Severity

 Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.89% (84th percentile)

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  • Snyk IDSNYK-CENTOS7-LIBCURL-1972254
  • published26 Jul 2021
  • disclosed4 Oct 2017
Report a new vulnerability Found a mistake?

Introduced: 4 Oct 2017

CVE-2017-1000254  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

There is no fixed version for Centos:7 libcurl.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libcurl package and not the libcurl package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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.

References