Bug 1983720 (CVE-2021-36222) - CVE-2021-36222 krb5: Sending a request containing PA-ENCRYPTED-CHALLENGE padata element without using FAST could result in NULL dereference in KDC which leads to DoS
Summary: CVE-2021-36222 krb5: Sending a request containing PA-ENCRYPTED-CHALLENGE pada...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2021-36222
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1983729 1983733 1983728 1992011
Blocks: 1983721
TreeView+ depends on / blocked
 
Reported: 2021-07-19 15:27 UTC by Michael Kaplan
Modified: 2021-09-21 12:26 UTC (History)
51 users (show)

Fixed In Version: krb5 1.19.2
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in krb5. This flaw allows an unauthenticated attacker to cause a NULL dereference in the KDC by sending a request containing a PA-ENCRYPTED-CHALLENGE padata element without using FAST. The highest threat from this vulnerability is to system availability.
Clone Of:
Environment:
Last Closed: 2021-09-21 12:26:21 UTC


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:3576 0 None None None 2021-09-21 08:39:18 UTC

Description Michael Kaplan 2021-07-19 15:27:58 UTC
In MIT krb5 releases 1.16 and later, an unauthenticated attacker can cause a null dereference in the KDC by sending a request containing a PA-ENCRYPTED-CHALLENGE padata element without using FAST.

Comment 7 Marco Benatto 2021-08-10 14:31:03 UTC
On ec_verify() function, when armor key is NULL it should return ENOENT, however due to a logic error the return value is overwritten by 0 in case k5memdup0() call is executed successfully before the check for armor key is executed. This leads to a NULL pointer dereference when further handling the armor key.
An attacker may leverage this by sending crafted requests to KDC server, leading it to crash and causing a DoS.

Comment 8 Marco Benatto 2021-08-10 14:33:26 UTC
Created krb5 tracking bugs for this issue:

Affects: fedora-all [bug 1992011]

Comment 9 errata-xmlrpc 2021-09-21 08:39:14 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:3576 https://access.redhat.com/errata/RHSA-2021:3576

Comment 10 Product Security DevOps Team 2021-09-21 12:26:21 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-36222


Note You need to log in before you can comment on or make changes to this bug.