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Fencer Vulns
critical 9.8

CVE-2020-10188 in the critical feed json

utility.c in telnetd in netkit telnet through 0.17 allows remote attackers to execute arbitrary code via short writes or urgent data, becau…

published 2020-03-06 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-2649

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
74.3%
EPSS 74.3% chance of exploitation in 30 days, percentile 99.4%
public exploits
0
none known

Summary

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.

Patch / fix

  • inetutils Debian 14, Debian 13, Debian 12 2:1.9.4-12
  • netkit-telnet-ssl Debian 14, Debian 13, Debian 12 0.17.17+0.1-2woody3

debian advisories DEBIAN-CVE-2020-10188

  • inetutils Ubuntu 18.04 LTS 2:1.9.4-3ubuntu0.1
  • inetutils Ubuntu 20.04 LTS 2:1.9.4-11ubuntu0.1
  • inetutils Ubuntu Pro 14.04 LTS 2:1.9.2-1ubuntu0.1~esm2
  • inetutils Ubuntu Pro 16.04 LTS 2:1.9.4-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2020-10188

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • krb5-appl RHEL 6 1.0.1-10.el6_10
  • krb5-appl-servers RHEL 6 1.0.1-10.el6_10
  • telnet RHEL 7 1:0.17-65.el7_8
  • telnet-server RHEL 7 1:0.17-65.el7_8
  • telnet RHEL 6 1:0.17-49.el6_10
  • telnet-server RHEL 6 1:0.17-49.el6_10
  • telnet RHEL 8 1:0.17-73.el8_1.1
  • telnet-server RHEL 8 1:0.17-73.el8_1.1

red hat advisories RHSA-2022:0158RHSA-2022:0011RHSA-2020:1349RHSA-2020:1342RHSA-2020:1334RHSA-2020:1335

  • krb5-appl SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +12 more 1.0.3-3.3.1

suse advisories SUSE-SU-2020:1533-1

  • inetutils Arch Linux 2.0-1

arch linux advisories AVG-1003

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-10188 updated cvss 9.8

telnet-server: no bounds checks in nextitem() function allows to remotely execute arbitrary code

  • Red Hat Enterprise Linux 5 telnet
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) telnet 0.17-73.el8_1.1, telnet-server 0.17-73.el8_1.1
    fixed: vendor fix RHSA-2020:1318
  • Red Hat Enterprise Linux AppStream E4S (v. 8.0) telnet 0.17-73.el8_0.1, telnet-server 0.17-73.el8_0.1
    fixed: vendor fix RHSA-2020:1342
  • Red Hat Enterprise Linux Client (v. 7) telnet 0.17-65.el7_8, telnet-server 0.17-65.el7_8 Red Hat Enterprise Linux ComputeNode (v. 7) telnet 0.17-65.el7_8, telnet-server 0.17-65.el7_8
    fixed: vendor fix RHSA-2020:1334
  • Red Hat Enterprise Linux Desktop (v. 6) telnet 0.17-49.el6_10, krb5-appl 1.0.1-10.el6_10, telnet-server 0.17-49.el6_10, krb5-appl-servers 1.0.1-10.el6_10 Red Hat Enterprise Linux HPC Node (v. 6) telnet 0.17-49.el6_10, krb5-appl 1.0.1-10.el6_10, telnet-server 0.17-49.el6_10, krb5-appl-servers 1.0.1-10.el6_10 Red Hat Enterprise Linux Server (v. 6) telnet 0.17-49.el6_10, krb5-appl 1.0.1-10.el6_10, telnet-server 0.17-49.el6_10, krb5-appl-servers 1.0.1-10.el6_10
    fixed: vendor fix RHSA-2020:1349
  • Red Hat Enterprise Linux Server (v. 7) telnet 0.17-65.el7_8, telnet-server 0.17-65.el7_8
    fixed: vendor fix RHSA-2020:1334
  • Red Hat Enterprise Linux Server AUS (v. 7.6) telnet 0.17-65.el7_6, telnet-server 0.17-65.el7_6
    fixed: vendor fix RHSA-2022:0011
  • Red Hat Enterprise Linux Server AUS (v. 7.7) telnet 0.17-65.el7_7, telnet-server 0.17-65.el7_7
    fixed: vendor fix RHSA-2022:0158
show 7 more
  • Red Hat Enterprise Linux Server E4S (v. 7.6) telnet 0.17-65.el7_6, telnet-server 0.17-65.el7_6
    fixed: vendor fix RHSA-2022:0011
  • Red Hat Enterprise Linux Server E4S (v. 7.7) telnet 0.17-65.el7_7, telnet-server 0.17-65.el7_7
    fixed: vendor fix RHSA-2022:0158
  • Red Hat Enterprise Linux Server TUS (v. 7.6) telnet 0.17-65.el7_6, telnet-server 0.17-65.el7_6
    fixed: vendor fix RHSA-2022:0011
  • Red Hat Enterprise Linux Server TUS (v. 7.7) telnet 0.17-65.el7_7, telnet-server 0.17-65.el7_7
    fixed: vendor fix RHSA-2022:0158
  • Red Hat Enterprise Linux Workstation (v. 6) telnet 0.17-49.el6_10, krb5-appl 1.0.1-10.el6_10, telnet-server 0.17-49.el6_10, krb5-appl-servers 1.0.1-10.el6_10
    fixed: vendor fix RHSA-2020:1349
  • Red Hat Enterprise Linux Workstation (v. 7) telnet 0.17-65.el7_8, telnet-server 0.17-65.el7_8
    fixed: vendor fix RHSA-2020:1334
  • Red Hat Enterprise Linux AppStream (v. 8) telnet 0.17-73.el8_1.1 Red Hat Enterprise Linux AppStream E4S (v. 8.0) telnet 0.17-73.el8_0.1 Red Hat Enterprise Linux Client (v. 7) telnet 0.17-65.el7_8 Red Hat Enterprise Linux ComputeNode (v. 7) telnet 0.17-65.el7_8 Red Hat Enterprise Linux Desktop (v. 6) telnet 0.17-49.el6_10, krb5-appl-clients 1.0.1-10.el6_10 Red Hat Enterprise Linux HPC Node (v. 6) telnet 0.17-49.el6_10, krb5-appl-clients 1.0.1-10.el6_10
    +4 more products
    Red Hat Enterprise Linux Server (v. 6) telnet 0.17-49.el6_10, krb5-appl-clients 1.0.1-10.el6_10 Red Hat Enterprise Linux Server (v. 7) telnet 0.17-65.el7_8 Red Hat Enterprise Linux Workstation (v. 6) telnet 0.17-49.el6_10, krb5-appl-clients 1.0.1-10.el6_10 Red Hat Enterprise Linux Workstation (v. 7) telnet 0.17-65.el7_8
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

74.34% chance of exploitation in the next 30 days, higher than 99.4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.