CVE-2014-1692

Vulnerability

The hash_buffer function in schnorr.c of OpenSSH through 6.4 does not initialize certain data structures when an error condition occurs during EVP_Digest* operations. This flaw exists only within the experimental J-PAKE (Password Authenticated Key Exchange) protocol code, which is not enabled by default; it requires modifying Makefile.inc or using specific compiler flags to activate [4]. The commit fixing the issue (revision 1.10) was made on 2014-01-29 and added explicit clearing of returned digest and length for error cases [4]. HP-UX running HP Secure Shell before versions A.06.20.010 (B.11.11), A.06.20.011 (B.11.23), and A.06.20.012 (B.11.31) are affected [2].

Exploitation

An attacker can trigger the vulnerability by sending crafted network traffic that causes an error in the J-PAKE hashing routine, provided the server has been compiled with J-PAKE support enabled [3][4]. No default OpenSSH installations are vulnerable because the code is not reachable unless explicitly enabled by the administrator [3]. The attacker does not need authentication but must be able to initiate a connection to the SSH server running the modified build [4].

Impact

A successful exploitation leads to denial of service via memory corruption, as indicated by the CVE description and HP bulletins [1][2]. The HP advisory categorizes this under "Buffer Errors (CWE-119)" and rates the CVSS v2 impact as partial confidentiality, integrity, and availability, though the primary demonstrated outcome is remote denial of service [2]. The CVE description also notes "unspecified other impact" is possible, but the references do not provide details on code execution [3][4].

Mitigation

For upstream OpenSSH, the fix was committed in revision 1.10 of schnorr.c on 2014-01-29 [4]. Users should ensure their OpenSSH builds are up to date (post-6.4). For HP-UX users, HP released updates for HP Secure Shell: A.06.20.010 (B.11.11), A.06.20.011 (B.11.23), and A.06.20.012 (B.11.31) [2]. Since J-PAKE is experimental and never enabled by default, the most effective workaround is to not enable J-PAKE support in any environment. There is no indication that CVE-2014-1692 is listed in the CISA Known Exploited Vulnerabilities catalog.