CVE-2018-16839
SASL password overflow via integer overflow
Project curl Security Advisory, October 31st 2018 - Permalink
VULNERABILITY
libcurl contains a buffer overrun in the SASL authentication code.
The internal function Curl_auth_create_plain_message
fails to correctly verify that the passed in lengths for name and
password are not too long, then calculates a buffer size to
allocate.
On systems with a 32 bit size_t, the math to calculate
the buffer size triggers an integer overflow when the username length
exceeds 1GB and the password name length is close to 2GB in size. This
integer overflow usually causes a very small buffer to actually get
allocated instead of the intended very huge one, making the use of that
buffer end up in a heap buffer overflow.
(This bug is very similar to CVE-2018-14618.)
INFO
The affected function can only be invoked when using POP3(S), IMAP(S) or SMTP(S).
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2018-16839 to this issue.
CWE-131: Incorrect Calculation of Buffer Size
Severity: Low
AFFECTED VERSIONS
This issue is only present on 32 bit systems. It also requires the username field to use more than 2GB of memory, which should be rare.
- Affected versions: libcurl 7.33.0 to and including 7.61.1
- Not affected versions: libcurl < 7.33.0 and >= 7.62.0
- Introduced-in: https://github.com/curl/curl/commit/c56f9797e7feb7c2dc
curl is used by many applications, but not always advertised as such.
SOLUTION
In libcurl version 7.62.0, the integer overflow is avoided. An error is returned if a too long username is attempted.
RECOMMENDATIONS
We suggest you take one of the following actions immediately, in order of preference:
A - Upgrade curl to version 7.62.0
B - Apply the patch to your version and rebuild
C - Put length restrictions on the username field you can pass to libcurl
TIMELINE
It was reported to the curl project on September 6, 2018. We contacted distros@openwall on October 22.
curl 7.62.0 was released on October 31 2018, coordinated with the publication of this advisory.
CREDITS
- Reported-by: Harry Sintonen
- Patched-by: Daniel Stenberg
Thanks a lot!