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Fencer Vulns
high 7.5

CVE-2021-36222 in the critical feed json

ec_verify in kdc/kdc_preauth_ec.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.18.4 and 1.19.x before 1.19.2…

published 2021-07-22 5 y ago modified 2026-10-14 26 d ago also EUVD-2021-22842

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
10.5%
EPSS 10.5% chance of exploitation in 30 days, percentile 95%
public exploits
0
none known

Summary

ec_verify in kdc/kdc_preauth_ec.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.18.4 and 1.19.x before 1.19.2 allows remote attackers to cause a NULL pointer dereference and daemon crash. This occurs because a return value is not properly managed in a certain situation.

Patch / fix

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • krb5 Debian 14, Debian 13, Debian 12 1.18.3-6

debian advisories DEBIAN-CVE-2021-36222

  • krb5 Ubuntu 18.04 LTS 1.16-2ubuntu0.4
  • krb5 Ubuntu 20.04 LTS 1.17-6ubuntu4.3

ubuntu advisories UBUNTU-CVE-2021-36222

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 RHEL 8 1.18.2-8.3.el8_4
  • libkadm5 RHEL 8 1.18.2-8.3.el8_4
  • krb5-libs RHEL 8 1.18.2-8.3.el8_4
  • krb5-pkinit RHEL 8 1.18.2-8.3.el8_4
  • krb5-server RHEL 8 1.18.2-8.3.el8_4
  • krb5-server-ldap RHEL 8 1.18.2-8.3.el8_4
  • krb5-workstation RHEL 8 1.18.2-8.3.el8_4

red hat advisories RHSA-2021:3576

  • rhnlib Manager Client Tools 15-BETA 5.0.1-159000.6.30.1
  • ansible Manager Client Tools 15-BETA 2.9.27-159000.3.9.1
  • grafana Manager Client Tools 15-BETA 9.5.8-159000.4.24.1
  • mgr-push Manager Client Tools 15-BETA 5.0.1-159000.4.21.1
  • spacecmd Manager Client Tools 15-BETA 5.0.1-159000.6.42.1
  • python-hwdata Manager Client Tools 15-BETA 2.3.5-159000.5.13.1
  • python-pyvmomi Manager Client Tools 15-BETA 6.7.3-159000.3.6.1
  • dracut-saltboot Manager Client Tools Beta for SLE Micro 5, Manager Client Tools 15-BETA 0.1.1681904360.84ef141-159000.3.30.1

suse advisories SUSE-SU-2024:0196-1SUSE-SU-2024:0191-1SUSE-SU-2022:4439-1SUSE-SU-2022:4437-1SUSE-SU-2022:4428-1SUSE-SU-2022:3676-1

  • krb5 openSUSE Tumbleweed 1.19.2-2.2
  • grafana openSUSE Tumbleweed 8.3.4-1.1
  • samba openSUSE Leap 15.3 4.15.4+git.324.8332acf1a63-150300.3.25.3
  • ldb openSUSE Leap 15.3 2.4.1-150300.3.10.1
  • tdb openSUSE Leap 15.3 1.4.4-150300.3.3.2
  • krb5 openSUSE Leap 15.3 1.19.2-150300.8.3.2
  • sssd openSUSE Leap 15.3 1.16.1-150300.23.17.3
  • talloc openSUSE Leap 15.3 2.3.3-150300.3.3.2

opensuse advisories openSUSE-SU-2024:10899-1openSUSE-SU-2024:11816-1openSUSE-SU-2022:0283-1openSUSE-SU-2021:1182-1openSUSE-SU-2021:2800-1

  • krb5 Rocky Linux 8 1.18.2-8.3.el8_4

rocky linux advisories RLSA-2021:3576

  • krb5 Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 1.18.4-r0

alpine advisories ALPINE-CVE-2021-36222

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • krb5 CBL-Mariner 2.0 1.19.2-1

azure linux advisories AZL-6607

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • krb5 Arch Linux 1.19.2-1

arch linux advisories AVG-2173

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-2021-36222 updated cvss 7.5

krb5: Sending a request containing PA-ENCRYPTED-CHALLENGE padata element without using FAST could result in NULL dereference in KDC which leads to DoS

  • Red Hat Enterprise Linux 7 krb5, libkadm5, krb5-libs, krb5-pkinit, krb5-server, krb5-server-ldap, +1 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux BaseOS (v. 8) krb5 1.18.2-8.3.el8_4, libkadm5 1.18.2-8.3.el8_4, krb5-libs 1.18.2-8.3.el8_4, krb5-pkinit 1.18.2-8.3.el8_4, krb5-server 1.18.2-8.3.el8_4, krb5-server-ldap 1.18.2-8.3.el8_4, +1 more
    fixed: vendor fix RHSA-2021:3576
  • Red Hat Enterprise Linux 9 krb5, libkadm5, krb5-libs, krb5-pkinit, krb5-server, krb5-server-ldap, +2 more Red Hat JBoss Core Services krb5 Red Hat JBoss Enterprise Application Platform 6 krb5
    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

cisa ICSA-23-348-10 updated cvss 7.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

10.51% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
Technology feeds

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.