The Heimdal Software Kerberos 5 implementation is vulnerable to a null pointer dereferance. An attacker with network access to an application that depends on the vulnerable code path can cause the application to crash.

The fix for CVE-2022-3437 included changing memcmp to be constant time and a workaround for a compiler bug by adding "!= 0" comparisons to the result of memcmp. When these patches were backported to the heimdal-7.7.1 and heimdal-7.8.0 branches (and possibly other branches) a logic inversion sneaked in causing the validation of message integrity codes in gssapi/arcfour to be inverted.

Heimdall Application Dashboard through 2.5.4 allows reflected and stored XSS via "Application name" to the "Add application" page. The stored XSS will be triggered in the "Application list" page.

Heimdal before 7.7.1 allows attackers to cause a NULL pointer dereference in a SPNEGO acceptor via a preferred_mech_type of GSS_C_NO_OID and a nonzero initial_response value to send_accept.

PAC parsing in MIT Kerberos 5 (aka krb5) before 1.19.4 and 1.20.x before 1.20.1 has integer overflows that may lead to remote code execution (in KDC, kadmind, or a GSS or Kerberos application server) on 32-bit platforms (which have a resultant heap-based buffer overflow), and cause a denial of service on other platforms. This occurs in krb5_pac_parse in lib/krb5/krb/pac.c. Heimdal before 7.7.1 has "a similar bug."

Heimdal before 7.7.1 allows remote attackers to execute arbitrary code because of an invalid free in the ASN.1 codec used by the Key Distribution Center (KDC).

Heimdal is an implementation of ASN.1/DER, PKIX, and Kerberos. Versions prior to 7.7.1 are vulnerable to a denial of service vulnerability in Heimdal's PKI certificate validation library, affecting the KDC (via PKINIT) and kinit (via PKINIT), as well as any third-party applications using Heimdal's libhx509. Users should upgrade to Heimdal 7.7.1 or 7.8. There are no known workarounds for this issue.

Heimdal.Wizard.exe installer in Heimdal Premium Security 2.5.395 and earlier has insecure permissions, which allows unprivileged local users to elevate privileges to SYSTEM via the "Browse For Folder" window accessible by triggering a "Repair" on the MSI package located in C:\Windows\Installer.

A flaw was found in samba's Heimdal KDC implementation, versions 4.8.x up to, excluding 4.8.12, 4.9.x up to, excluding 4.9.8 and 4.10.x up to, excluding 4.10.3, when used in AD DC mode. A man in the middle attacker could use this flaw to intercept the request to the KDC and replace the user name (principal) in the request with any desired user name (principal) that exists in the KDC effectively obtaining a ticket for that principal.

In the client side of Heimdal before 7.6.0, failure to verify anonymous PKINIT PA-PKINIT-KX key exchange permits a man-in-the-middle attack. This issue is in krb5_init_creds_step in lib/krb5/init_creds_pw.c.