Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | krb5 | 1.18.3-1 | — |
| Debian 13 | krb5 | 1.18.3-1 | — |
| Debian 12 | krb5 | 1.18.3-1 | — |
| Debian 10 | krb5 | 1.17-3+deb10u1 | DSA-4795-1 |
| Debian 9 | krb5 | 1.15-1+deb9u2 | DLA-2437-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | krb5 | 1.17-6ubuntu4.1 | USN-4635-1 |
| Ubuntu 18.04 LTS | krb5 | 1.16-2ubuntu0.2 | USN-4635-1 |
| Ubuntu 16.04 LTS | krb5 | 1.13.2+dfsg-5ubuntu2.2 | USN-4635-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 14.04 LTS | krb5 | 1.12+dfsg-2ubuntu5.4+esm2 | USN-4635-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | krb5 +7 | 1.18.2-8.el8 | RHSA-2021:1593 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Rhev Hypervisor 4 | redhat-virtualization-host +1 | 4.4.6-20210527.3.el8_4 | RHSA-2021:2239 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | krb5 | 1.18.2-8.el8 | RLSA-2021:1593 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | krb5 | 1.16.3-3.15.1 | SUSE-SU-2020:3377-1 |
| SLES 15 SP1 | krb5 | 1.16.3-3.15.1 | SUSE-SU-2020:3377-1 |
| SLES 15 | krb5 | 1.15.2-6.12.2 | SUSE-SU-2020:3375-1 |
| SLES 12 SP5 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLES 12 SP4 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLES 12 SP2 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLES for SAP 15 | krb5 | 1.15.2-6.12.2 | SUSE-SU-2020:3375-1 |
| SLES for SAP 12 SP5 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLES for SAP 12 SP4 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLES for SAP 12 SP3 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLES for SAP 12 SP2 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SLE HPC 15 | krb5 | 1.15.2-6.12.2 | SUSE-SU-2020:3375-1 |
| SUSE OpenStack Cloud Crowbar 9 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SUSE OpenStack Cloud Crowbar 8 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SUSE OpenStack Cloud 9 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SUSE OpenStack Cloud 8 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SUSE OpenStack Cloud 7 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SUSE HPE Helion OpenStack 8 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
| SUSE Enterprise Storage 5 | krb5 | 1.12.5-40.40.2 | SUSE-SU-2020:3379-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | krb5 | 1.19.2-3.1 | openSUSE-SU-2024:11549-1 |
| openSUSE Leap 15.2 | krb5 +1 | 1.16.3-lp152.5.13.1 | openSUSE-SU-2020:2062-1 |
| openSUSE Leap 15.1 | krb5 +1 | 1.16.3-lp151.2.15.1 | openSUSE-SU-2020:2037-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | krb5 | 1.18.3-r0 | — |
| Alpine v3.23 | krb5 | 1.18.3-r0 | — |
| Alpine v3.22 | krb5 | 1.18.3-r0 | — |
| Alpine v3.21 | krb5 | 1.18.3-r0 | — |
| Alpine v3.20 | krb5 | 1.18.3-r0 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | krb5 | 1.18.3-r0 | — |
| Alpine v3.18 | krb5 | 1.18.3-r0 | — |
| Alpine v3.17 | krb5 | 1.18.3-r0 | — |
| Alpine v3.16 | krb5 | 1.18.3-r0 | — |
| Alpine v3.15 | krb5 | 1.18.3-r0 | — |
| Alpine v3.14 | krb5 | 1.18.3-r0 | — |
| Alpine v3.13 | krb5 | 1.18.3-r0 | — |
| Alpine v3.12 | krb5 | 1.18.3-r0 | — |
| Alpine v3.11 | krb5 | 1.17.2-r0 | — |
| Alpine v3.10 | krb5 | 1.17.2-r0 | — |
| Alpine v3.9 | krb5 | 1.15.5-r1 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | libkadm5 +6 | 1.15.1-37.amzn2.2.3 | ALAS2-2022-1845 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | libkadm5 +6 | 1.18.2-8.el8 | ELSA-2021-1593 |
| Oracle Linux 7 | libkadm5 +6 | 1.15.1-50.0.1.el7 | ELSA-2021-9294 |
Advisories 21
- SSA-398330 SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5 Siemens ProductCERT · Oct 13, 2026
- WID-SEC-2025-0227 IBM QRadar SIEM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 11, 2026
- RHSA-2021:2239 Red Hat Security Advisory: Red Hat Virtualization Host security update [ovirt-4.4.6] Red Hat Security Advisories (RHSA) · Aug 4, 2026
- RHSA-2021:1593 Red Hat Security Advisory: krb5 security update Red Hat Security Advisories (RHSA) · Aug 4, 2026
- USN-4635-1 krb5 vulnerability Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-4795-1 krb5 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2437-1 krb5 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2021:1593 Moderate: krb5 security update Rocky Linux Security Advisories · Feb 4, 2026
- openSUSE-SU-2024:11549-1 krb5-1.19.2-3.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3379-1 Security update for krb5 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:2062-1 Security update for krb5 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3375-1 Security update for krb5 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3377-1 Security update for krb5 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:2037-1 Security update for krb5 SUSE / openSUSE Security Updates · Feb 4, 2026
- ICSA-23-348-10 Siemens SIMATIC S7-1500 CISA ICS & IT advisories · Aug 12, 2025
- WID-SEC-2022-0602 IBM Security Verify Access: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 17, 2024
- WID-SEC-2023-0065 Oracle MySQL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 27, 2023
- WID-SEC-2022-1481 MIT Kerberos: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Jan 11, 2023
- ALAS2-2022-1845 Moderate: krb5 security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 10, 2022
- ELSA-2021-9294 Important: krb5 security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jun 11, 2021
- ELSA-2021-1593 Moderate: krb5 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 25, 2021
References
- [debian-lts-announce] 20201107 [SECURITY] [DLA 2437-1] krb5 security update mailing-list
- FEDORA-2020-32193cbbe6 vendor-advisory
- FEDORA-2020-27b577ab23 vendor-advisory
- GLSA-202011-17 vendor-advisory
- FEDORA-2020-0df38b2843 vendor-advisory
- DSA-4795 vendor-advisory
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://security.netapp.com/advisory/ntap-20210513-0002/
- https://github.com/krb5/krb5/commit/57415dda6cf04e73ffc3723be518eddfae599bfd
- https://security.netapp.com/advisory/ntap-20201202-0001/
- [bookkeeper-issues] 20210628 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8 mailing-list
- [bookkeeper-issues] 20210629 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8 mailing-list
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html