CVE-2025-59089 — Python-kdcproxy: remote dos via unbounded tcp upstream buffering

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
latchset / kdcproxy	affected 0 before 1.1.0
Red Hat / Red Hat Enterprise Linux 10	unaffected 0:1.0.0-19.el10_1 before *
Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support	unaffected 0:1.0.0-19.el10_0 before *
Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support	unaffected 0:0.3.2-3.el7_9.3 before *
Red Hat / Red Hat Enterprise Linux 8	unaffected 8100020251103113748.143e9e98 before *
Red Hat / Red Hat Enterprise Linux 8	unaffected 8100020251028161822.823393f5 before *
Red Hat / Red Hat Enterprise Linux 8.2 Advanced Update Support	unaffected 8020020251106022345.792f4060 before *
Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support	unaffected 8040020251103205102.5b01ab7e before *
Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On	unaffected 8040020251103205102.5b01ab7e before *
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support	unaffected 8060020251030180424.ada582f1 before *
Red Hat / Red Hat Enterprise Linux 8.6 Telecommunications Update Service	unaffected 8060020251030180424.ada582f1 before *
Red Hat / Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions	unaffected 8060020251030180424.ada582f1 before *
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service	unaffected 8080020251029082621.b0a6ceea before *
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions	unaffected 8080020251029082621.b0a6ceea before *
Red Hat / Red Hat Enterprise Linux 9	unaffected 0:1.0.0-9.el9_7 before *
Red Hat / Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions	unaffected 0:1.0.0-7.el9_0.1 before *
Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions	unaffected 0:1.0.0-7.el9_2.1 before *
Red Hat / Red Hat Enterprise Linux 9.4 Extended Update Support	unaffected 0:1.0.0-7.el9_4.1 before *
Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support	unaffected 0:1.0.0-9.el9_6 before *

CWE

CWE-770

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

CVE

No English description supplied.

https://github.com/latchset/kdcproxy/commit/c7675365aa20be11f03247966336c7613cac84e1