CVE-2020-10188

CVE-2020-10188 is a critical-severity vulnerability in Netkit Telnet Project Netkit Telnet with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 75% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-120.

Key facts

• Severity: Critical (CVSS 3.x base score 9.8)
• CVSS v2: 10.0
• EPSS exploit prediction: 75% (99th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-120
• Affected product: Netkit Telnet Project Netkit Telnet
• Published: 2020-03-06
• Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.

How severe is CVE-2020-10188?

CVE-2020-10188 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-10188 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 75% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-10188?

CVE-2020-10188 primarily affects Netkit Telnet Project Netkit Telnet. In total, 358 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-10188?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-10188 published?

CVE-2020-10188 was published on 2020-03-06 and last updated on 2026-06-17.

References

• https://appgateresearch.blogspot.com/2020/02/bravestarr-fedora-31-netkit-telnetd_28.html
• https://github.com/krb5/krb5-appl/blob/d00cd671dfe945791b33d4f1f6a5c57ae1667ef8/telnet/telnetd/utility.c#L205-L216
• https://lists.debian.org/debian-lts-announce/2020/05/msg00012.html
• https://lists.debian.org/debian-lts-announce/2020/08/msg00038.html
• 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
• https://www.arista.com/en/support/advisories-notices/security-advisories/10702-security-advisory-48
• https://www.oracle.com/security-alerts/cpuApr2021.html
• http://www.openwall.com/lists/oss-security/2026/01/20/8

Affected products (358)

• cpe:2.3:a:netkit_telnet_project:netkit_telnet:*:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
• cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
• cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
• cpe:2.3:o:arista:eos:4.24.0f:*:*:*:*:*:*:*
• cpe:2.3:a:oracle:communications_performance_intelligence_center:10.4.0.2:*:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:-:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r1:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r10:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r10-s1:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r10-s2:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r11:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s1:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s10:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s11:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s12:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s13:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s14:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s15:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s3:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s4:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s6:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r12-s8:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r13:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r2:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r3:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r4:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r5:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r6:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r7:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r8:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3:r9:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3r12:*:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3x48:-:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3x48:d10:*:*:*:*:*:*
• cpe:2.3:o:juniper:junos:12.3x48:d100:*:*:*:*:*:*

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