RTSP RTP buffer over-read

Project curl Security Advisory, March 14th 2018 - Permalink

VULNERABILITY

curl can be tricked into copying data beyond end of its heap based buffer.

When asked to transfer an RTSP URL, curl could calculate a wrong data length to copy from the read buffer. The memcpy call would copy data from the heap following the buffer to a storage area that would subsequently be delivered to the application (if it didn't cause a crash). We've managed to get it to reach several hundreds bytes out of range.

This could lead to information leakage or a denial of service for the application if the server offering the RTSP data can trigger this.

We are not aware of any exploit of this flaw.

INFO

This bug was introduced in January 2010 in this commit when RTSP support was first added.

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2018-1000122 to this issue.

CWE-126: Buffer Over-read

Severity: Medium

AFFECTED VERSIONS

• Affected versions: curl 7.20.0 to and including curl 7.58.0
• Not affected versions: curl < 7.20.0 and curl >= 7.59.0

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

THE SOLUTION

In curl version 7.59.0, curl makes sure that this code never gets told to copy more data than it is allowed to read from the buffer.

A patch for CVE-2018-1000122 is available.

RECOMMENDATIONS

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

A - Upgrade curl to version 7.59.0

B - Apply the patch to your version and rebuild

TIME LINE

It was reported to the curl project on February 20, 2018

We contacted distros@openwall on March 8, 2018.

curl 7.59.0 was released on March 14 2018, coordinated with the publication of this advisory.

CREDITS

Detected by OSS-fuzz. Assisted by Max Dymond. Patch by Daniel Stenberg.

Thanks a lot!