NVD / CVE Program· CNA mitre

CVE-2020-10188: utility.c in telnetd in netkit telnet through 0.17 allows remote attackers to execute arbitrary code via short writes or urgent data…

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: This week (action score 61/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 74.3% (FIRST EPSS); higher than 99.4% of all records.
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.
Fixed version: inetutils (Debian:12) 2:1.9.4-12; netkit-telnet-ssl (Debian:12) 0.17.17+0.1-2woody3; inetutils (Debian:8) 2:1.9.2.39.3a460-3+deb8u1.
Mentioned 5 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Don’t wait for the next maintenance window. Upgrade to inetutils (Debian:12) 2:1.9.4-12; netkit-telnet-ssl (Debian:12) 0.17.17+0.1-2woody3; inetutils (Debian:8) 2:1.9.2.39.3a460-3+deb8u1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

utility.c in telnetd in netkit telnet through 0.17 allows remote attackers to execute arbitrary code via short writes or urgent data, because of a buffer overflow involving the netclear and nextitem functions.

Published: Mar 6, 2020
Updated: Jun 16, 2026
EPSS: 74.3% · 99th percentile
CWE: CWE-120

Report tools

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Action score

This week

Don’t wait for the next maintenance window.

CVSS: 39 / 40 · 9.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 22 / 30 · 74.3%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
netkit telnet project	netkit telnet	cpe:2.3:a:netkit_telnet_project:netkit_telnet
fedoraproject	fedora	cpe:2.3:o:fedoraproject:fedora
debian	debian linux	cpe:2.3:o:debian:debian_linux
arista	eos	cpe:2.3:o:arista:eos
oracle	communications performance intelligence center	cpe:2.3:a:oracle:communications_performance_intelligence_center
juniper	junos	cpe:2.3:o:juniper:junos

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

arista eosup to 4.20.15 inclusive
arista eos4.23 and later · up to 4.23.3m inclusive
arista eos4.22 and later · up to 4.22.4m inclusive
arista eos4.21.0 and later · up to 4.21.10m inclusive
arista eos4.24.0f
debian debian linux8.0
debian debian linux9.0
fedoraproject fedora30

+12 more rows

fedoraproject fedora31
fedoraproject fedora32
juniper junos12.3
juniper junos12.3r12
juniper junos12.3x48
juniper junos12.3x50
juniper junos15.1
juniper junos15.1x49
juniper junos15.1x49-d140
juniper junos15.1x49-d150
juniper junos15.1x49-d160
juniper junos15.1x49-d30

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	inetutils	before 2:1.9.4-12	2:1.9.4-12
Debian:12	netkit-telnet-ssl	before 0.17.17+0.1-2woody3	0.17.17+0.1-2woody3
Debian:8	inetutils	before 2:1.9.2.39.3a460-3+deb8u1	2:1.9.2.39.3a460-3+deb8u1
Debian:9	inetutils	before 2:1.9.4-2+deb9u1	2:1.9.4-2+deb9u1
Red Hat:enterprise_linux:6::client	krb5-appl	before 0:1.0.1-10.el6_10	0:1.0.1-10.el6_10
Red Hat:enterprise_linux:6::client	krb5-appl-servers	before 0:1.0.1-10.el6_10	0:1.0.1-10.el6_10
Red Hat:enterprise_linux:6::client	telnet	before 1:0.17-49.el6_10	1:0.17-49.el6_10
Red Hat:enterprise_linux:6::client	telnet-server	before 1:0.17-49.el6_10	1:0.17-49.el6_10
Red Hat:enterprise_linux:7::client	telnet	before 1:0.17-65.el7_8	1:0.17-65.el7_8
Red Hat:enterprise_linux:7::client	telnet-server	before 1:0.17-65.el7_8	1:0.17-65.el7_8
Red Hat:enterprise_linux:8::appstream	telnet	before 1:0.17-73.el8_1.1	1:0.17-73.el8_1.1
Red Hat:enterprise_linux:8::appstream	telnet-server	before 1:0.17-73.el8_1.1	1:0.17-73.el8_1.1
Red Hat:rhel_aus:7.6::server	telnet	before 1:0.17-65.el7_6	1:0.17-65.el7_6
Red Hat:rhel_aus:7.6::server	telnet-debuginfo	before 1:0.17-65.el7_6	1:0.17-65.el7_6
Red Hat:rhel_aus:7.6::server	telnet-server	before 1:0.17-65.el7_6	1:0.17-65.el7_6
Red Hat:rhel_aus:7.7::server	telnet	before 1:0.17-65.el7_7	1:0.17-65.el7_7
Red Hat:rhel_aus:7.7::server	telnet-debuginfo	before 1:0.17-65.el7_7	1:0.17-65.el7_7
Red Hat:rhel_aus:7.7::server	telnet-server	before 1:0.17-65.el7_7	1:0.17-65.el7_7
Red Hat:rhel_e4s:8.0::appstream	telnet	before 1:0.17-73.el8_0.1	1:0.17-73.el8_0.1
Red Hat:rhel_e4s:8.0::appstream	telnet-server	before 1:0.17-73.el8_0.1	1:0.17-73.el8_0.1
SUSE:HPE Helion OpenStack 8	krb5-appl	before 1.0.3-3.3.1	1.0.3-3.3.1

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:inetutils	2:1.9.4-12 · Debian:12	Package registry (OSV)
debian:netkit-telnet-ssl	0.17.17+0.1-2woody3 · Debian:12	Package registry (OSV)
red hat:krb5-appl	0:1.0.1-10.el6_10 · Red Hat:enterprise_linux:6::client	Package registry (OSV)
red hat:krb5-appl-servers	0:1.0.1-10.el6_10 · Red Hat:enterprise_linux:6::client	Package registry (OSV)
red hat:telnet	1:0.17-73.el8_1.1 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:telnet-debuginfo	1:0.17-65.el7_6 · Red Hat:rhel_aus:7.6::server	Package registry (OSV)
red hat:telnet-server	1:0.17-73.el8_1.1 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
suse:krb5-appl	1.0.3-3.3.1 · SUSE:HPE Helion OpenStack 8	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

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.

No dated events beyond publication.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-22-0062 · Jan 19, 2022(RedHat Güvenlik Güncellemesi)
TR-22-0009 · Jan 5, 2022(RedHat Güvenlik Güncellemesi)
TR-21-0331 · Apr 21, 2021(Oracle Güvenlik Uyarısı Yayınladı)
TR-20-857 · Oct 16, 2020(Juniper Güvenlik Güncellemeleri Yayınladı)
TR-20-634 · Aug 24, 2020(Inetutils Güvenlik Güncellemesi Yayınladı)

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

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: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

The bug in code

The whole CWE-120 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:45 PM UTC

For records you follow, these changes also arrive as notifications. →

References

appgateresearch.blogspot.com/2020/02/bravestarr-fedora-31-netkit-telnetd_28.html

Show all references (10 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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