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, because of a buffer overflow involving the netclear and nextitem functions.

Published: 2020-03-06 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-10188 is rated High Risk (79/100): CVSS Critical severity, with high exploitation likelihood (EPSS 74.51%, 99th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +66.11% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

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

Exploit prediction scoring system (EPSS) score for CVE-2020-10188

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 8.40% 74.51% +66.11%
2 2026-05-10 9.58% 8.40% -1.17%
3 2026-04-11 — 9.58% —

Full EPSS history (41 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-10188

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
10.0 2.0 HIGH
AV:N/AC:L/Au:N/C:C/I:C/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:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 10.0 [email protected]

Weakness enumeration for CVE-2020-10188

OS Trackers for CVE-2020-10188

vendor priority summary link
debian not yet assigned CVE-2020-10188 not yet assigned priority: Debian including 3 source packages (inetutils, netkit-telnet, netkit-telnet-ssl), 11 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 11. https://security-tracker.debian.org/tracker/CVE-2020-10188
redhat high — https://access.redhat.com/security/cve/CVE-2020-10188
suse high CVE-2020-10188 severity important: SUSE including 8 source package names (krb5-appl-clients-1.0.3-3.3.1, krb5-appl-servers-1.0.3-3.3.1, …), 75 product×package rows across 32 product lines (HPE Helion OpenStack 8, SUSE Enterprise Storage 5, … (32 product lines)): Fixed 42, Known Not Affected 33. https://www.suse.com/security/cve/CVE-2020-10188/
ubuntu medium CVE-2020-10188 medium priority: Ubuntu including 3 source packages (inetutils, netkit-telnet, netkit-telnet-ssl), 50 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 18, ignored 12, DNE 7, needs-triage 7, released 6. https://ubuntu.com/security/CVE-2020-10188

Affected software / configurations for CVE-2020-10188

Vendor Product Version Raw CPE
netkit_telnet_project netkit_telnet <= 0.17 cpe:2.3:a:netkit_telnet_project:netkit_telnet:*:*:*:*:*:*:*:*
fedoraproject fedora 30 cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
arista eos <= 4.20.15 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.21.0, <= 4.21.10m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.22, <= 4.22.4m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.23, <= 4.23.3m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos 4.24.0f cpe:2.3:o:arista:eos:4.24.0f:*:*:*:*:*:*:*
oracle communications_performance_intelligence_center 10.4.0.2 cpe:2.3:a:oracle:communications_performance_intelligence_center:10.4.0.2:*:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:-:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r1:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r10:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r10-s1:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r10-s2:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r11:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s1:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s10:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s11:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s12:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s13:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s14:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s15:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s3:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s4:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s6:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r12-s8:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r13:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r2:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r3:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r4:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r5:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r6:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r7:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r8:*:*:*:*:*:*
juniper junos 12.3 cpe:2.3:o:juniper:junos:12.3:r9:*:*:*:*:*:*
juniper junos 12.3r12 cpe:2.3:o:juniper:junos:12.3r12:*:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:-:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d10:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d100:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d15:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d20:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d25:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d30:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d35:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d40:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d45:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d50:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d51:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d55:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d60:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d65:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d66:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d70:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d75:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d80:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d85:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d90:*:*:*:*:*:*
juniper junos 12.3x48 cpe:2.3:o:juniper:junos:12.3x48:d95:*:*:*:*:*:*
juniper junos 12.3x50 cpe:2.3:o:juniper:junos:12.3x50:-:*:*:*:*:*:*
juniper junos 12.3x50 cpe:2.3:o:juniper:junos:12.3x50:d20:*:*:*:*:*:*
juniper junos 12.3x50 cpe:2.3:o:juniper:junos:12.3x50:d30:*:*:*:*:*:*
juniper junos 12.3x50 cpe:2.3:o:juniper:junos:12.3x50:d35:*:*:*:*:*:*
juniper junos 12.3x50 cpe:2.3:o:juniper:junos:12.3x50:d40:*:*:*:*:*:*
juniper junos 12.3x50 cpe:2.3:o:juniper:junos:12.3x50:d45:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:-:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:a1:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f1:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f2:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f2-s1:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f2-s2:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f2-s3:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f2-s4:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f3:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f4:*:*:*:*:*:*
juniper junos 15.1 cpe:2.3:o:juniper:junos:15.1:f5:*:*:*:*:*:*

References for CVE-2020-10188

URL Tags
https://appgateresearch.blogspot.com/2020/02/bravestarr-fedora-31-netkit-telnetd_28.html Third Party Advisory
https://github.com/krb5/krb5-appl/blob/d00cd671dfe945791b33d4f1f6a5c57ae1667ef8/telnet/telnetd/utility.c#L205-L216 Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00012.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/08/msg00038.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7FMTRRQTYKWZD2GMXX3GLZV46OLPCLVK/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HLU6FL24BSQQEB2SJC26NLJ2MANQDA7M/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3VJ6V2Z3JRNJOBVHSOPMAC76PSSKG6A/
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-telnetd-EFJrEzPx Third Party Advisory
https://www.arista.com/en/support/advisories-notices/security-advisories/10702-security-advisory-48 Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/01/20/8
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