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Fencer Intel
medium 5.3

CVE-2018-15919 json

Remotely observable behaviour in auth-gss2.c in OpenSSH through 7.8 could be used by remote attackers to detect existence of users on a tar…

published 2018-08-28 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-7775

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.5%
EPSS 3.5% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

Remotely observable behaviour in auth-gss2.c in OpenSSH through 7.8 could be used by remote attackers to detect existence of users on a target system when GSS2 is in use. NOTE: the discoverer states 'We understand that the OpenSSH developers do not want to treat such a username enumeration (or "oracle") as a vulnerability.'

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-15919 updated cvss 5.3

openssh: User enumeration via malformed packets in authentication requests

  • Red Hat Enterprise Linux 7 openssh, openssh-cavs, openssh-ldap, openssh-keycat, openssh-server, openssh-askpass, +3 more Red Hat Enterprise Linux 8 openssh, openssh-cavs, openssh-ldap, openssh-keycat, openssh-server, openssh-askpass, +2 more Red Hat Virtualization 4 openssh
    affected: workaround, no fix planned “If GSSAPI Authentication is not required, this flaw can be mitigated by changing the global configuration in `/etc/ssh/sshd_config` from `GSSAPIAuthentication yes` to `GSSAPIAuthentication no`.”
  • Red Hat Enterprise Linux 5 openssh Red Hat Enterprise Linux 6 openssh, openssh-ldap, openssh-server, openssh-askpass, openssh-clients, pam_ssh_agent_auth
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
10 mo ago

Exploit prediction

3.51% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 3.0 5.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.