CVE-2025-59088
Description
If kdcproxy receives a request for a realm which does not have server addresses defined in its configuration, by default, it will query SRV records in the DNS zone matching the requested realm name. This creates a server-side request forgery vulnerability, since an attacker could send a request for a realm matching a DNS zone where they created SRV records pointing to arbitrary ports and hostnames (which may resolve to loopback or internal IP addresses). This vulnerability can be exploited to probe internal network topology and firewall rules, perform port scanning, and exfiltrate data. Deployments where the "use_dns" setting is explicitly set to false are not affected.
Mitigation
To mitigate this issue before a final fix can be applied, set "use_dns" parameter to false in the global section of the kdcproxy.conf file. This will disable the use of DNS to find Active Directory servers so it may break the service if DNS is needed.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.6 | N/A | 8.6 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Access Control
Technical Impact: Bypass Protection Mechanism
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
Acknowledgements
Red Hat would like to thank Arad Inbar for reporting this issue.
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