Bug 1801998 (CVE-2020-1730) - CVE-2020-1730 libssh: denial of service when handling AES-CTR (or DES) ciphers
Summary: CVE-2020-1730 libssh: denial of service when handling AES-CTR (or DES) ciphers
Keywords:
Status: NEW
Alias: CVE-2020-1730
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1802422 1814517 1822529
Blocks: 1795471
TreeView+ depends on / blocked
 
Reported: 2020-02-12 05:27 UTC by Dhananjay Arunesh
Modified: 2020-07-08 04:58 UTC (History)
29 users (show)

Fixed In Version: libssh 0.8.9, libssh 0.9.4
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the way libssh handled AES-CTR (or DES ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat from this vulnerability is system availability.
Clone Of:
Environment:
Last Closed:


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Description Dhananjay Arunesh 2020-02-12 05:27:24 UTC
A vulnerability was found in libssh through version 0.8.0, where a malicious client or server could crash the counterpart implemented with libssh AES-CTR ciphers are used and don't get fully initialized. It will crash when it tries to cleanup the AES-CTR ciphers when closing the connection.

Comment 2 Huzaifa S. Sidhpurwala 2020-02-13 05:58:01 UTC
Acknowledgments:

Name: libssh team
Upstream: Yasheng Yang (Google)

Comment 3 Huzaifa S. Sidhpurwala 2020-02-13 06:01:24 UTC
Mitigation:

Disable AES-CTR ciphers (and DES in libssh 0.8). If you implement a server using libssh we advise to use a prefork model so each session runs in an own process. If you have implemented your server this way this is not really an issue. The client will kill its own connection.

Comment 8 Huzaifa S. Sidhpurwala 2020-04-09 09:26:21 UTC
External References:

https://www.libssh.org/security/advisories/CVE-2020-1730.txt

Comment 9 Huzaifa S. Sidhpurwala 2020-04-09 09:27:04 UTC
Created libssh tracking bugs for this issue:

Affects: fedora-all [bug 1822529]


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