#VU56828 NULL pointer dereference in Kerberos 5 - CVE-2021-37750

Vulnerability identifier: #VU56828

Vulnerability risk: Medium

CVSSv4.0: 4.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-37750

CWE-ID: CWE-476

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Kerberos 5
Client/Desktop applications / Software for system administration

Vendor: MIT

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in the Key Distribution Center (KDC) in kdc/do_tgs_req.c. A remote user can pass specially crafted data via the FAST inner body that lacks a server field, trigger a NULL pointer dereference error and perform a denial of service (DoS) attack.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Kerberos 5: 1.18 - 1.19.2

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External links
https://github.com/krb5/krb5/commit/d775c95af7606a51bf79547a94fa52ddd1cb7f49
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MFCLW7D46E4VCREKKH453T5DA4XOLHU2/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.