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CVE-2020-28196

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via...

7.5 HighFix available

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

4.42%Up 2.6 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-674
Updated
2026-11-02
CVE List 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-674
Updated
2026-11-02
EUVDEUVD-2020-20680 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
EUVD-2020-20680
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-2wgw-3mv7-47xf 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via...

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
GHSA-2wgw-3mv7-47xf
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-674
Updated
2026-11-02
OSVALPINE-CVE-2020-28196 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
ALPINE-CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVBELL-CVE-2020-28196 7.5

CVE-2020-28196 does not affect BellSoft software

Record
BELL-CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 15 moreShow less
OSV 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2020-28196 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
DEBIAN-CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVOESA-2021-1026 7.5

krb5 security update

Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography.\r\n\r\n Security Fix(es):\r\n\r\n MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.(CVE-2020-28196)\r\n\r\n

Record
OESA-2021-1026
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRHSA-2021:1593 7.5

Red Hat Security Advisory: krb5 security update

Record
RHSA-2021:1593
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRHSA-2021:2239 8.2

Red Hat Security Advisory: Red Hat Virtualization Host security update [ovirt-4.4.6]

Record
RHSA-2021:2239
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Updated
2026-11-02
OSVRLSA-2021:1593 7.5

Moderate: krb5 security update

Kerberos is a network authentication system, which can improve the security of your network by eliminating the insecure practice of sending passwords over the network in unencrypted form. It allows clients and servers to authenticate to each other with the help of a trusted third party, the Kerberos key distribution center (KDC).

Security Fix(es):

  • krb5: unbounded recursion via an ASN.1-encoded Kerberos message in lib/krb5/asn.1/asn1_encode.c may lead to DoS (CVE-2020-28196)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Rocky Linux 8.4 Release Notes linked from the References section.

Record
RLSA-2021:1593
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2020-28196 7.5

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.

Record
UBUNTU-CVE-2020-28196
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2021-0022 No score

Updated krb5 packages fix a security vulnerability

MIT Kerberos 5 (aka krb5) before 1.17.2 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit (CVE-2020-28196).

Record
MGASA-2021-0022
Updated
2026-11-02
OSVopenSUSE-SU-2020:2037-1 No score

Security update for krb5

This update for krb5 fixes the following security issue:

  • CVE-2020-28196: Fixed an unbounded recursion via an ASN.1-encoded Kerberos message (bsc#1178512).

This update was imported from the SUSE:SLE-15-SP1:Update update project.

Record
openSUSE-SU-2020:2037-1
Updated
2026-11-02
OSVopenSUSE-SU-2020:2062-1 No score

Security update for krb5

This update for krb5 fixes the following security issue:

  • CVE-2020-28196: Fixed an unbounded recursion via an ASN.1-encoded Kerberos message (bsc#1178512).

This update was imported from the SUSE:SLE-15-SP1:Update update project.

Record
openSUSE-SU-2020:2062-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:11549-1 No score

krb5-1.19.2-3.1 on GA media

These are all security issues fixed in the krb5-1.19.2-3.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11549-1
Updated
2026-11-02
OSVSUSE-SU-2020:3375-1 No score

Security update for krb5

This update for krb5 fixes the following security issue:

  • CVE-2020-28196: Fixed an unbounded recursion via an ASN.1-encoded Kerberos message (bsc#1178512).
Record
SUSE-SU-2020:3375-1
Updated
2026-11-02
OSVSUSE-SU-2020:3377-1 No score

Security update for krb5

This update for krb5 fixes the following security issue:

  • CVE-2020-28196: Fixed an unbounded recursion via an ASN.1-encoded Kerberos message (bsc#1178512).
Record
SUSE-SU-2020:3377-1
Updated
2026-11-02
OSVSUSE-SU-2020:3379-1 No score

Security update for krb5

This update for krb5 fixes the following security issue:

  • CVE-2020-28196: Fixed an unbounded recursion via an ASN.1-encoded Kerberos message (bsc#1178512).
Record
SUSE-SU-2020:3379-1
Updated
2026-11-02
OSVUSN-4635-1 No score

krb5 vulnerability

Demi Obenour discovered that Kerberos incorrectly handled certain ASN.1. An attacker could possibly use this issue to cause a denial of service.

Record
USN-4635-1
Updated
2026-11-02

Affected products

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Affected packages

Affected packages
PackageAffectedFixed
krb5
Alpine:v3.10
 before 1.17.2-r0
1.17.2-r0
krb5
Alpine:v3.11
 before 1.17.2-r0
1.17.2-r0
krb5
Alpine:v3.12
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.13
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.14
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.15
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.16
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.17
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.18
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.19
 before 1.18.3-r0
1.18.3-r0
Show 69 moreShow less
Affected packages
PackageAffectedFixed
krb5
Alpine:v3.20
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.21
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.22
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.23
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.24
 before 1.18.3-r0
1.18.3-r0
krb5
Alpine:v3.9
 before 1.15.5-r1
1.15.5-r1
krb5
Debian:12
 before 1.18.3-1
1.18.3-1
krb5
Debian:13
 before 1.18.3-1
1.18.3-1
krb5
Debian:14
 before 1.18.3-1
1.18.3-1
krb5
Debian:9
 before 1.15-1+deb9u2, plus listed versions
1.15-11.15-1+deb9u1
1.15-1+deb9u2
krb5
Debian:10
 before 1.17-3+deb10u1, plus listed versions
1.17-3
1.17-3+deb10u1
krb5
Mageia:7
 before 1.17-2.1.mga7
1.17-2.1.mga7
krb5
openEuler:20.03-LTS
 before 1.18.2-2.oe1
1.18.2-2.oe1
krb5
openEuler:20.03-LTS-SP1
 before 1.18.2-2.oe1
1.18.2-2.oe1
krb5
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-debugsource
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-devel
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-devel-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-libs
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-libs-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-pkinit
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-pkinit-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-server
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-server-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-server-ldap
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-server-ldap-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-workstation
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5-workstation-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
libkadm5
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
libkadm5-debuginfo
Red Hat:enterprise_linux:8::baseos
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
redhat-virtualization-host
Red Hat:rhev_hypervisor:4.4::el8
From an advisory covering 3 CVEs
 before 0:4.4.6-20210527.3.el8_4
0:4.4.6-20210527.3.el8_4
redhat-virtualization-host-image-update
Red Hat:rhev_hypervisor:4.4::el8
From an advisory covering 3 CVEs
 before 0:4.4.6-20210527.3.el8_4
0:4.4.6-20210527.3.el8_4
krb5
Rocky Linux:8
 before 0:1.18.2-8.el8
0:1.18.2-8.el8
krb5
SUSE:Linux Enterprise High Performance Computing 15-ESPOS
 before 1.15.2-6.12.2
1.15.2-6.12.2
krb5
SUSE:Linux Enterprise High Performance Computing 15-LTSS
 before 1.15.2-6.12.2
1.15.2-6.12.2
krb5
SUSE:Linux Enterprise Server 15-LTSS
 before 1.15.2-6.12.2
1.15.2-6.12.2
krb5
SUSE:Linux Enterprise Server for SAP Applications 15
 before 1.15.2-6.12.2
1.15.2-6.12.2
krb5
SUSE:Linux Enterprise Module for Basesystem 15 SP1
 before 1.16.3-3.15.1
1.16.3-3.15.1
krb5
SUSE:Linux Enterprise Module for Basesystem 15 SP2
 before 1.16.3-3.15.1
1.16.3-3.15.1
krb5
SUSE:Linux Enterprise Module for Server Applications 15 SP1
 before 1.16.3-3.15.1
1.16.3-3.15.1
krb5
SUSE:Linux Enterprise Module for Server Applications 15 SP2
 before 1.16.3-3.15.1
1.16.3-3.15.1
krb5
SUSE:HPE Helion OpenStack 8
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:OpenStack Cloud 7
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:OpenStack Cloud 8
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:OpenStack Cloud 9
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:OpenStack Cloud Crowbar 8
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:OpenStack Cloud Crowbar 9
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server for SAP Applications 12 SP2
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server for SAP Applications 12 SP3
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server for SAP Applications 12 SP4
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Software Development Kit 12 SP5
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server 12 SP2-LTSS
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server 12 SP2-BCL
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server 12 SP3-LTSS
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server 12 SP3-BCL
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server 12 SP4-LTSS
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server 12 SP5
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
SUSE:Enterprise Storage 5
 before 1.12.5-40.40.2
1.12.5-40.40.2
krb5
Ubuntu:Pro:14.04:LTS
 before 1.12+dfsg-2ubuntu5.4+esm2, plus listed versions
1.10.1+dfsg-6.1ubuntu11.11.3+dfsg-3ubuntu21.12+dfsg-2ubuntu11.12+dfsg-2ubuntu21.12+dfsg-2ubuntu3
Show 8 moreShow less
1.12+dfsg-2ubuntu41.12+dfsg-2ubuntu4.21.12+dfsg-2ubuntu51.12+dfsg-2ubuntu5.11.12+dfsg-2ubuntu5.21.12+dfsg-2ubuntu5.31.12+dfsg-2ubuntu5.41.12+dfsg-2ubuntu5.4+esm1
1.12+dfsg-2ubuntu5.4+esm2
krb5
Ubuntu:16.04:LTS
 before 1.13.2+dfsg-5ubuntu2.2, plus listed versions
1.13.2+dfsg-21.13.2+dfsg-31.13.2+dfsg-41.13.2+dfsg-51.13.2+dfsg-5ubuntu11.13.2+dfsg-5ubuntu21.13.2+dfsg-5ubuntu2.1
1.13.2+dfsg-5ubuntu2.2
krb5
Ubuntu:18.04:LTS
 before 1.16-2ubuntu0.2, plus listed versions
1.15.1-21.16-21.16-2build11.16-2ubuntu0.1
1.16-2ubuntu0.2
krb5
Ubuntu:20.04:LTS
 before 1.17-6ubuntu4.1, plus listed versions
1.17-61.17-6ubuntu31.17-6ubuntu4
1.17-6ubuntu4.1
krb5
openSUSE:Leap 15.1
 before 1.16.3-lp151.2.15.1
1.16.3-lp151.2.15.1
krb5-mini
openSUSE:Leap 15.1
 before 1.16.3-lp151.2.15.1
1.16.3-lp151.2.15.1
krb5
openSUSE:Leap 15.2
 before 1.16.3-lp152.5.13.1
1.16.3-lp152.5.13.1
krb5-mini
openSUSE:Leap 15.2
 before 1.16.3-lp152.5.13.1
1.16.3-lp152.5.13.1
krb5
openSUSE:Tumbleweed
From an advisory covering 2 CVEs
 before 1.19.2-3.1
1.19.2-3.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-28196 is a high vulnerability (CVSS 7.5) in Mit Kerberos 5, published November 6, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 4.42%, the 91st percentile. Fixed in krb5 1.17.2-r0.

References

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