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CVE-2016-6515

68
FAUCET Score

CVE-2016-6515 is a denial-of-service vulnerability affecting OpenSSH versions prior to 7.3, including those in Fedora and OpenBSD. It allows remote attackers to consume significant CPU resources by sending excessively long passwords during authentication attempts. Rated 7.5 HIGH, this vulnerability requires no user interaction and can be exploited over the network, leading to system unavailability. While not actively exploited in the wild and lacking Metasploit/Nuclei modules, a proof-of-concept exploit exists on ExploitDB, and its high EPSS score indicates a significant likelihood of future exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
<= 7.2CPE matchmatch criteria
cpe:2.3:a:openbsd:openssh:*:p2:*:*:*:*:*:*
24CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:24:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
58.57%
Probability of exploitation in next 30 days
EPSS Percentile
99.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
ExploitDB: EDB-40888 · Dec 7, 2016
This CVE's current EPSS score of 0.5857 is in the 98th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

github_advisorypatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: openssh-0:7.4p1-11.el7
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: openssh
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: openssh

Vendor Advisories (1)

redhatCVE-2016-6515Moderate

openssh: Denial of service via very long passwords

Jul 21, 2016

References

openwall.com / lists/oss-security/2016/08/01/2
Third Party AdvisoryVDB Entry
packetstormsecurity.com / files/140070/OpenSSH-7.2-Denial-Of-Service.html
access.redhat.com / errata/RHSA-2017:2029
cert-portal.siemens.com / productcert/pdf/ssa-412672.pdf
cert-portal.siemens.com / productcert/pdf/ssa-676336.pdf
github.com / openssh/openssh-portable/commit/fcd135c9df440bcd2d5870405ad3311743d78d97
Issue TrackingPatch
lists.debian.org / debian-lts-announce/2018/09/msg00010.html
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/X2L6RW34VFNXYNVVN2CN73YAGJ5VMTFU
security.freebsd.org / advisories/FreeBSD-SA-17:06.openssh.asc
security.netapp.com / advisory/ntap-20171130-0003
support.hpe.com / hpsc/doc/public/display
exploit-db.com / exploits/40888
oracle.com / technetwork/security-advisory/cpuoct2017-3236626.html
securityfocus.com / bid/92212
securitytracker.com / id/1036487