CVE-2016-6515

Exp

The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which allows remote attackers to cause a denial of service (crypt CPU consumption) via a long string.

Published: 2016-08-07 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-6515 is rated High Exploit Risk (74.6/100): CVSS High severity, with high exploitation likelihood (EPSS 57.67%, 99th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2016-6515

EDB-ID Source Kind Published Link
40888 exploit_db edb 2016-12-07 Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2016-6515

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 77.09% 57.67% -19.42%
2 2026-05-27 75.79% 77.09% +1.30%
3 2026-05-02 — 75.79% —

Full EPSS history (51 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-6515

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.8 2.0 HIGH
AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 6.9 [email protected]

Weakness enumeration for CVE-2016-6515

OS Trackers for CVE-2016-6515

vendor priority summary link
debian not yet assigned CVE-2016-6515 not yet assigned priority: Debian including 1 source packages (openssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-6515
redhat medium — https://access.redhat.com/security/cve/CVE-2016-6515
suse medium CVE-2016-6515 severity moderate: SUSE including 355 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 446 product×package rows across 62 product lines (HPE Helion OpenStack 8, SUSE Liberty Linux 7, … (62 product lines)): Fixed 264, Known Affected 157, Known Not Affected 25. https://www.suse.com/security/cve/CVE-2016-6515/
ubuntu medium CVE-2016-6515 medium priority: Ubuntu including 1 source packages (openssh), 6 status rows across 6 suites (precise, trusty, upstream, xenial, yakkety, zesty): released 4, not-affected 2. https://ubuntu.com/security/CVE-2016-6515

Affected software / configurations for CVE-2016-6515

Vendor Product Version Raw CPE
openbsd openssh <= 7.2 cpe:2.3:a:openbsd:openssh:*:p2:*:*:*:*:*:*
fedoraproject fedora 24 cpe:2.3:o:fedoraproject:fedora:24:*:*:*:*:*:*:*

References for CVE-2016-6515

URL Tags
http://openwall.com/lists/oss-security/2016/08/01/2 Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/140070/OpenSSH-7.2-Denial-Of-Service.html
http://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html
http://www.securityfocus.com/bid/92212
http://www.securitytracker.com/id/1036487
https://access.redhat.com/errata/RHSA-2017:2029
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://cert-portal.siemens.com/productcert/pdf/ssa-676336.pdf
https://github.com/openssh/openssh-portable/commit/fcd135c9df440bcd2d5870405ad3311743d78d97 Issue Tracking Patch
https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X2L6RW34VFNXYNVVN2CN73YAGJ5VMTFU/
https://security.FreeBSD.org/advisories/FreeBSD-SA-17:06.openssh.asc
https://security.netapp.com/advisory/ntap-20171130-0003/
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03779en_us
https://www.exploit-db.com/exploits/40888/
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