CVE-2019-3823

SMTP end-of-response out-of-bounds read

Project curl Security Advisory, February 6th 2019 - Permalink

VULNERABILITY

libcurl contains a heap out-of-bounds read in the code handling the end-of-response for SMTP.

If the buffer passed to smtp_endofresp() isn't null terminated and contains no character ending the parsed number, and len is set to 5, then the strtol() call reads beyond the allocated buffer. The read contents will not be returned to the caller.

INFO

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2019-3823 to this issue.

CWE-125: Out-of-bounds Read

Severity: Low

AFFECTED VERSIONS

• Affected versions: libcurl 7.34.0 to and including 7.63.0
• Not affected versions: libcurl < 7.34.0 and curl >= 7.64.0
• Introduced-in: https://github.com/curl/curl/commit/2766262a68

libcurl is used by many applications, but not always advertised as such.

SOLUTION

• Fixed-in: https://github.com/curl/curl/commit/39df4073e5413fcdbb5a38d

RECOMMENDATIONS

We suggest you take one of the following actions immediately, in order of preference:

A - Upgrade curl to version 7.64.0

B - Apply the patch to your version and rebuild

C - Turn off SMTP

TIMELINE

The issue was reported to the curl project on January 18, 2019. A patch was communicated to the reporter on January 19, 2019. We contacted distros@openwall on January 28.

curl 7.64.0 was released on February 6 2019, coordinated with the publication of this advisory.

CREDITS

• Reported-by: Brian Carpenter (Geeknik Labs)
• Patched-by: Daniel Gustafsson

Thanks a lot!