CVE-2017-1000254
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (8.14%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.0
- 7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 8.14% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-119
- Affected
- haxx/libcurl
- Source
- cve@mitre.org
EPSS 8.1% since 27 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.debian.org/security/2017/dsa-3992
- http://www.securityfocus.com/bid/101115Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1039509Third Party Advisory, VDB Entry
- https://access.redhat.com/errata/RHSA-2018:2486
- https://access.redhat.com/errata/RHSA-2018:3558
- https://curl.haxx.se/673d0cd8.patchPatch, Vendor Advisory
- https://curl.haxx.se/docs/adv_20171004.htmlPatch, Vendor Advisory
- 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/101115Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1039509Third Party Advisory, VDB Entry
- https://access.redhat.com/errata/RHSA-2018:2486
- https://access.redhat.com/errata/RHSA-2018:3558
- https://curl.haxx.se/673d0cd8.patchPatch, Vendor Advisory
- https://curl.haxx.se/docs/adv_20171004.htmlPatch, Vendor Advisory
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.