# CVE-2026-107708: MIT krb5 NULL pointer dereference in KDC get_pac_princ_with_realm

Source: https://junglewise.ai/threats/cve-2026-107708-mit-krb5-through-1-22-2-contains-a-null-pointer-dereference  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-08. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-107708 · Severity: medium · CVSS 4.9 · Published 2026-10-08

MIT krb5 is an implementation of the Kerberos authentication protocol used to verify user identities in enterprise networks. A vulnerability in the KDC (Key Distribution Center) allows a compromised or malicious cross-realm KDC to send a specially crafted authentication request that crashes the krb5kdc service, preventing users from authenticating and causing a denial of service.

Technologies: [Mit Krb5](https://junglewise.ai/threats/technologies/krb5). Vendors: [Mit](https://junglewise.ai/threats/vendors/mit).

## Quick answers

**Is CVE-2026-107708 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-107708 being exploited in the wild.

**How severe is CVE-2026-107708?** Medium severity, with a CVSS score of 4.9, published 8 October 2026.

**Which products and versions are affected?** Mit Krb5 through 1.22.2.

**Is there a fix for CVE-2026-107708?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-107708 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-107708?** Check whether you run Mit Krb5 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The KDC's get_pac_princ_with_realm() function contains a NULL pointer dereference when processing S4U2Proxy (service-for-user-to-proxy) requests with a PAC (Privilege Attribute Certificate) containing a malformed client name. The function returns success while leaving the client principal NULL, which is subsequently dereferenced, causing krb5kdc to crash. Attack requires network access to the KDC and a trust relationship with a cross-realm KDC.

## Affected products

- MIT krb5 through 1.22.2

## Timeline

- 2026-10-08: disclosed

## References

- [https://github.com/krb5/krb5](https://github.com/krb5/krb5)
- [https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c](https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c)

## Related threats

- [MIT krb5 integer underflow in berval2tl_data function](https://junglewise.ai/threats/cve-2026-11850-mit-krb5-integer-underflow-in-berval2tl-data-function)
- [MIT Kerberos message spoofing via RC4-HMAC-MD5 MD5 collisions](https://junglewise.ai/threats/cve-2025-3576-mit-kerberos-message-spoofing-via-rc4-hmac-md5-md5-collisions)