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Fencer Intel
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 6y ago modified 4mo 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

Is CVE-2020-10188 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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, 2026-11-09).

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 Intel 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.