CVE-2020-28196

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.

Published: 2020-11-06 Last update: 2025-12-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-28196 is rated Moderate Risk (57.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.95%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-28196

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-30 0.37% 0.95% +0.59%
2 2026-05-18 1.29% 0.37% -0.93%
3 2026-03-28 — 1.29% —

Full EPSS history (27 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-28196

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-28196

OS Trackers for CVE-2020-28196

vendor priority summary link
alpine — CVE-2020-28196: 1 source package rows (krb5); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2020-28196
debian not yet assigned CVE-2020-28196 not yet assigned priority: Debian including 1 source packages (krb5), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-28196
gentoo low CVE-2020-28196: 1 GLSA(s) (202011-17), 1 atom(s) (app-crypt/mit-krb5); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-28196
redhat medium — https://access.redhat.com/security/cve/CVE-2020-28196
suse high CVE-2020-28196 severity important: SUSE including 414 source package names (0.1.0:krb5-1.16.3-3.15.1, 0.1.75:krb5-1.16.3-3.15.1, …), 663 product×package rows across 139 product lines (Container caasp/v4/389-ds, Container caasp/v4/busybox, … (139 product lines)): Fixed 479, Known Affected 157, Known Not Affected 27. https://www.suse.com/security/cve/CVE-2020-28196/
ubuntu medium CVE-2020-28196 medium priority: Ubuntu including 1 source packages (krb5), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): released 5, needs-triage 1. https://ubuntu.com/security/CVE-2020-28196

Affected software / configurations for CVE-2020-28196

Vendor Product Version Raw CPE
mit kerberos_5 < 1.17.2 cpe:2.3:a:mit:kerberos_5:*:*:*:*:*:*:*:*
mit kerberos_5 >= 1.18.0, < 1.18.3 cpe:2.3:a:mit:kerberos_5:*:*:*:*:*:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*
netapp cloud_backup — cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
netapp oncommand_insight — cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
netapp oncommand_workflow_automation — cpe:2.3:a:netapp:oncommand_workflow_automation:-:*:*:*:*:*:*:*
netapp snapcenter — cpe:2.3:a:netapp:snapcenter:-:*:*:*:*:*:*:*
oracle communications_cloud_native_core_policy 1.14.0 cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*
oracle communications_offline_mediation_controller 12.0.0.3.0 cpe:2.3:a:oracle:communications_offline_mediation_controller:12.0.0.3.0:*:*:*:*:*:*:*
oracle communications_pricing_design_center 12.0.0.3.0 cpe:2.3:a:oracle:communications_pricing_design_center:12.0.0.3.0:*:*:*:*:*:*:*
oracle mysql_server <= 8.0.23 cpe:2.3:a:oracle:mysql_server:*:*:*:*:*:*:*:*

References for CVE-2020-28196

URL Tags
https://github.com/krb5/krb5/commit/57415dda6cf04e73ffc3723be518eddfae599bfd Patch Third Party Advisory
https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
https://lists.debian.org/debian-lts-announce/2020/11/msg00011.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/45KKOZQWIIIW5C45PJVGQ32AXBSYNBE7/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/73IGOG6CZAVMVNS4GGRMOLOZ7B6QVA7F/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KPH2V3WSQTELROZK3GFCPQDOFLKIZ6H5/
https://security.gentoo.org/glsa/202011-17 Third Party Advisory
https://security.netapp.com/advisory/ntap-20201202-0001/ Third Party Advisory
https://security.netapp.com/advisory/ntap-20210513-0002/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4795 Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Patch Third Party Advisory
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