TFTP Packet Buffer Overflow Vulnerability

Project curl Security Advisory, March 20th 2006 permalink

VULNERABILITY

libcurl uses the given file part of a TFTP URL in a manner that allows a malicious user to overflow a heap-based memory buffer due to the lack of boundary check.

This overflow happens if you pass in a URL with a TFTP protocol prefix ("tftp://"), using a valid host and a path part that is longer than 512 bytes.

The affected flaw can be triggered by a redirect, if curl/libcurl is told to follow redirects and an HTTP server points the client to a tftp URL with the characteristics described above.

There is no known exploit at the time of this writing.

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-1061 to this issue.

CWE-122: Heap-based Buffer Overflow

AFFECTED VERSIONS

• Affected versions: curl and libcurl 7.15.0 to and including 7.15.2
• Not affected versions: curl and libcurl 7.14.1 and earlier, 7.15.3 and later

libcurl 7.15.1 and 7.15.2 contain code that prevents this code from being executed on architectures where a struct is not of the same assumed packed size it has on x86, thus they are not vulnerable. For exact details on this, please review the code and patch.

Also note that (lib)curl is used by many applications, and not always advertised as such.

RECOMMENDATIONS

We suggest you take one of the following actions immediately:

A - Upgrade to curl and libcurl 7.15.3

B - Apply the patch https://curl.se/libcurl-tftp.patch to your libcurl version and install this

C - Build curl with TFTP disabled with configure --disable-tftp

TIME LINE

We were notified by Ulf Harnhammar on March 10th, 2006. His notification email contained a valid patch.

Daniel didn't read the mail until the 12th due to vacations.

curl 7.15.3 was released on March 20 2006, just before this flaw was publicly disclosed.

CREDITS

Reported to us by Ulf Harnhammar. Thanks a lot!