CVE-2025-59089 Python-kdcproxy: remote dos via unbounded tcp upstream buffering
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.
Problem types: cwe_id: CWE-770
description: Allocation of Resources Without Limits or Throttling
Affected products: vendor: latchset
product: kdcproxy
default_status: unaffected
vendor: Red Hat
product: Red Hat Enterprise Linux 10
cpes: cpe:/o:redhat:enterprise_linux:10.1
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 10.0 Extended Update Support
cpes: cpe:/o:redhat:enterprise_linux_eus:10.0
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 7 Extended Lifecycle Support
cpes: cpe:/o:redhat:rhel_els:7
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8
cpes: cpe:/a:redhat:enterprise_linux:8::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8
cpes: cpe:/a:redhat:enterprise_linux:8::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.2 Advanced Update Support
cpes: cpe:/a:redhat:rhel_aus:8.2::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
cpes: cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
cpe:/a:redhat:rhel_aus:8.4::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
cpes: cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
cpe:/a:redhat:rhel_aus:8.4::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
cpes: cpe:/a:redhat:rhel_tus:8.6::appstream
cpe:/a:redhat:rhel_e4s:8.6::appstream
cpe:/a:redhat:rhel_aus:8.6::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.6 Telecommunications Update Service
cpes: cpe:/a:redhat:rhel_tus:8.6::appstream
cpe:/a:redhat:rhel_e4s:8.6::appstream
cpe:/a:redhat:rhel_aus:8.6::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
cpes: cpe:/a:redhat:rhel_tus:8.6::appstream
cpe:/a:redhat:rhel_e4s:8.6::appstream
cpe:/a:redhat:rhel_aus:8.6::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.8 Telecommunications Update Service
cpes: cpe:/a:redhat:rhel_e4s:8.8::appstream
cpe:/a:redhat:rhel_tus:8.8::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
cpes: cpe:/a:redhat:rhel_e4s:8.8::appstream
cpe:/a:redhat:rhel_tus:8.8::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 9
cpes: cpe:/a:redhat:enterprise_linux:9::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
cpes: cpe:/a:redhat:rhel_e4s:9.0::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
cpes: cpe:/a:redhat:rhel_e4s:9.2::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 9.4 Extended Update Support
cpes: cpe:/a:redhat:rhel_eus:9.4::appstream
default_status: affected
vendor: Red Hat
product: Red Hat Enterprise Linux 9.6 Extended Update Support
cpes: cpe:/a:redhat:rhel_eus:9.6::appstream
default_status: affected
CVSS v3.1: attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 5.9
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
version: 3.1
Credits: lang: en
value: Red Hat would like to thank Arad Inbar for reporting this issue.
Published: 2025-11-12T16:40:50.725Z