CVE-2023-39975 — kdc/do_tgs_req

kdc/do_tgs_req.c in MIT Kerberos 5 (aka krb5) 1.21 before 1.21.2 has a double free that is reachable if an authenticated user can trigger an authorization-data handling failure. Incorrect data is copied from one ticket to another.

01What is this vulnerability?

kdc/do_tgs_req.c in MIT Kerberos 5 (aka krb5) 1.21 before 1.21.2 has a double free that is reachable if an authenticated user can trigger an authorization-data handling failure. Incorrect data is copied from one ticket to another.

02Affected products

Vendor	Product	Versions
n	a / n/a	n/a

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

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07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-08-16T00:00:00.000Z
• Last modified: 2026-02-25T17:20:11.934Z

09References

• web.mit.edu — https://web.mit.edu/kerberos/www/advisories/
• github.com — https://github.com/krb5/krb5/compare/krb5-1.21.1-final...krb5-1.21.2-final
• github.com — https://github.com/krb5/krb5/commit/88a1701b423c13991a8064feeb26952d3641d840
• security.netapp.com — https://security.netapp.com/advisory/ntap-20230915-0014/
• security.netapp.com — https://security.netapp.com/advisory/ntap-20240201-0008/
• security.netapp.com — https://security.netapp.com/advisory/ntap-20240201-0005/