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CVE-2017-1000254

UnknownEPSS 8.46%

Last modified

CVE-2017-1000254 is a vulnerability of currently unknown severity. 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. EPSS estimates a 8.46% chance of exploitation in the next 30 days.

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](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.

Metrics

EPSS Probability
8.46%

94.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
HaxxLibcurl7.7
HaxxLibcurl7.7.1
HaxxLibcurl7.7.2
HaxxLibcurl7.7.3
HaxxLibcurl7.8
HaxxLibcurl7.8.1
HaxxLibcurl7.9
HaxxLibcurl7.9.1
HaxxLibcurl7.9.2
HaxxLibcurl7.9.3
HaxxLibcurl7.9.4
HaxxLibcurl7.9.5
HaxxLibcurl7.9.6
HaxxLibcurl7.9.7
HaxxLibcurl7.9.8
HaxxLibcurl7.10
HaxxLibcurl7.10.1
HaxxLibcurl7.10.2
HaxxLibcurl7.10.3
HaxxLibcurl7.10.4
HaxxLibcurl7.10.5
HaxxLibcurl7.10.6
HaxxLibcurl7.10.7
HaxxLibcurl7.10.8
HaxxLibcurl7.11.0
HaxxLibcurl7.11.1
HaxxLibcurl7.11.2
HaxxLibcurl7.12.0
HaxxLibcurl7.12.1
HaxxLibcurl7.12.2
HaxxLibcurl7.12.3
HaxxLibcurl7.13.0
HaxxLibcurl7.13.1
HaxxLibcurl7.13.2
HaxxLibcurl7.14.0
HaxxLibcurl7.14.1
HaxxLibcurl7.15.0
HaxxLibcurl7.15.1
HaxxLibcurl7.15.2
HaxxLibcurl7.15.3
HaxxLibcurl7.15.4
HaxxLibcurl7.15.5
HaxxLibcurl7.16.0
HaxxLibcurl7.16.1
HaxxLibcurl7.16.2
HaxxLibcurl7.16.3
HaxxLibcurl7.16.4
HaxxLibcurl7.17.0
HaxxLibcurl7.17.1
HaxxLibcurl7.18.0

Showing 50 of 117 affected configurations. See NVD for the full list.

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is 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.
How severe is CVE-2017-1000254?
Severity scoring for CVE-2017-1000254 is pending analysis. The EPSS model estimates a 8.46% probability of exploitation in the next 30 days.
How do I fix CVE-2017-1000254?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2017-1000254?

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Source: NVD / NIST