python-kdcproxy TCP Upstream denial of service

Summaryinfo

A vulnerability classified as problematic has been found in python-kdcproxy. Impacted is an unknown function of the component TCP Upstream Handler. Performing a manipulation results in denial of service. This vulnerability is known as CVE-2025-59089. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in python-kdcproxy (version now known). It has been classified as problematic. This affects some unknown processing of the component TCP Upstream Handler. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. The summary by CVE is:

If an attacker causes kdcproxy to connect to an attacker-controlled KDC server (e.g. through server-side request forgery), they can exploit the fact that kdcproxy does not enforce bounds on TCP response length to conduct a denial-of-service attack. While receiving the KDC's response, kdcproxy copies the entire buffered stream into a new buffer on each recv() call, even when the transfer is incomplete, causing excessive memory allocation and CPU usage. Additionally, kdcproxy accepts incoming response chunks as long as the received data length is not exactly equal to the length indicated in the response header, even when individual chunks or the total buffer exceed the maximum length of a Kerberos message. This allows an attacker to send unbounded data until the connection timeout is reached (approximately 12 seconds), exhausting server memory or CPU resources. Multiple concurrent requests can cause accept queue overflow, denying service to legitimate clients.

The advisory is shared at bugzilla.redhat.com. This vulnerability is uniquely identified as CVE-2025-59089. The exploitability is told to be easy. It is possible to initiate the attack remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 275245 (RHEL 9 : python-kdcproxy (RHSA-2025:21139)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (275245), EUVD (EUVD-2025-131919) and CERT Bund (WID-SEC-2025-2586). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Red Hat Enterprise Linux
• Fedora Linux
• Oracle Linux

Productinfo

Type

• Programming Language Software

Name

• python-kdcproxy

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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