The kex_input_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3 allows remote attackers to cause a denial of service (memory cons
The kex_input_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3 allows remote attackers to cause a denial of service (memory consumption) by sending many duplicate KEXINIT requests. NOTE: a third party reports that "OpenSSH upstream does not consider this as a security issue."
- Published
- Dec 9, 2016
- Updated
- Jun 16, 2026
- EPSS
- 29.5% · 98th percentile
- CWE
- CWE-399
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
39
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 9 / 30 · 29.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| openbsd | openssh | cpe:2.3:a:openbsd:openssh |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- openbsd openssh6.8
- openbsd openssh6.9
- openbsd openssh7.0
- openbsd openssh7.1
- openbsd openssh7.2
- openbsd openssh7.3
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | openssh | before 1:7.3p1-2 | 1:7.3p1-2 |
| openSUSE:Tumbleweed | openssh | before 8.4p1-7.4 | 8.4p1-7.4 |
| SUSE:Linux Enterprise Desktop 12 SP2 | openssh | before 7.2p2-66.1 | 7.2p2-66.1 |
| SUSE:Linux Enterprise Desktop 12 SP2 | openssh-askpass-gnome | before 7.2p2-66.3 | 7.2p2-66.3 |
| SUSE:Linux Enterprise Server 11 SP4 | openssh | before 6.6p1-35.1 | 6.6p1-35.1 |
| SUSE:Linux Enterprise Server 11 SP4 | openssh-askpass-gnome | before 6.6p1-35.4 | 6.6p1-35.4 |
| SUSE:Linux Enterprise Server 11-SECURITY | openssh-openssl1 | before 6.6p1-18.1 | 6.6p1-18.1 |
| SUSE:Linux Enterprise Server 12 SP1 | openssh | before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
| SUSE:Linux Enterprise Server 12 SP1 | openssh-askpass-gnome | before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
| SUSE:OpenStack Cloud 5 | openssh | before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
| SUSE:OpenStack Cloud 5 | openssh-askpass-gnome | before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
Same product
openbsd: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-38408The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if 63This week
- CVE-2023-25136OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling.53Plan
- CVE-2018-15473OpenSSH through 7.7 is prone to a user enumeration vulnerability due to not delaying bailout for an invalid authenticating user until after 51Plan
- CVE-2016-6210sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the us50Plan
- CVE-2016-6515The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which48Plan
- CVE-2002-0640Buffer overflow in sshd in OpenSSH 2.3.1 through 3.3 may allow remote attackers to execute arbitrary code via a large number of responses du48Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:openssh | 1:7.3p1-2 · Debian:12 | Package registry (OSV) |
| opensuse:openssh | 8.4p1-7.4 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:openssh | 7.2p2-66.1 · SUSE:Linux Enterprise Desktop 12 SP2 | Package registry (OSV) |
| suse:openssh-askpass-gnome | 7.2p2-66.3 · SUSE:Linux Enterprise Desktop 12 SP2 | Package registry (OSV) |
| suse:openssh-openssl1 | 6.6p1-18.1 · SUSE:Linux Enterprise Server 11-SECURITY | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:7 | 2016-11-03 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoC-36 d
- Published
- TodaySep 30, 2026+3582 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-399 · Resource Management ErrorsCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h
- cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup
- www.openwall.com/lists/oss-security/2016/10/19/3
- www.openwall.com/lists/oss-security/2016/10/20/1
- www.securityfocus.com/bid/93776
- www.securitytracker.com/id/1037057
- bugzilla.redhat.com/show_bug.cgi?id=1384860
- cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
- ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig
- github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad
- security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc
- security.gentoo.org/glsa/201612-18
- security.netapp.com/advisory/ntap-20180201-0001/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.