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libssh2 Security Advisory: CVE-2019-3861

Out-of-bounds reads with specially crafted SSH packets

Project libssh2 Security Advisory, March 18 2019 - Permalink

VULNERABILITY

A server could send a specially crafted SSH packet with a padding length value greater than the packet length. This would result in a buffer read out of bounds when decompressing the packet or result in a corrupted packet value (CWE-130).

There are no known exploits of this flaw at this time.

INFO

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2019-3861 to this issue.

AFFECTED VERSIONS

THE SOLUTION

libssh2 1.8.1 ensures the length of the packet padding is less than the packet size minus 1.

A patch for this problem is available

RECOMMENDATIONS

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

A - Upgrade to libssh2 1.8.1 or later

B - Apply the patch and rebuild libssh2

TIME LINE

It was first reported to the libssh2 project on Dec 3 2018 by Chris Coulson.

libssh2 1.8.1 was released on March 18 2019, coordinated with the publication of this advisory.

CREDITS

Reported by Chris Coulson of Canonical Ltd.