Python-kdcproxy: remote dos via unbounded tcp upstream buffering

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Summary

CVECVE-2025-59089
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-11-12 17:15:38 UTC
Updated2026-04-20 09:16:08 UTC
DescriptionIf 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.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-770 | CWE-770 Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Latchset Kdcproxy affected 1.1.0 semver Not specified
CNA Red Hat Red Hat Enterprise Linux 10 unaffected 0:1.0.0-19.el10_1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support unaffected 0:1.0.0-19.el10_0 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support unaffected 0:0.3.2-3.el7_9.3 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 8100020251103113748.143e9e98 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 8100020251028161822.823393f5 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support unaffected 8020020251106022345.792f4060 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 8040020251103205102.5b01ab7e * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On unaffected 8040020251103205102.5b01ab7e * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 8060020251030180424.ada582f1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service unaffected 8060020251030180424.ada582f1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Update Services For SAP Solutions unaffected 8060020251030180424.ada582f1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 8080020251029082621.b0a6ceea * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 8080020251029082621.b0a6ceea * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:1.0.0-9.el9_7 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.0 Update Services For SAP Solutions unaffected 0:1.0.0-7.el9_0.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:1.0.0-7.el9_2.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support unaffected 0:1.0.0-7.el9_4.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:1.0.0-9.el9_6 * rpm Not specified

References

ReferenceSourceLinkTags
access.redhat.com/security/cve/CVE-2025-59089 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21142 [email protected] access.redhat.com
github.com/latchset/kdcproxy/pull/68 [email protected] github.com
access.redhat.com/errata/RHSA-2025:21820 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21819 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21141 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21821 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21818 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21140 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21748 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:22982 [email protected] access.redhat.com
github.com/latchset/kdcproxy/commit/c7675365aa20be11f03247966336c7613cac... af854a3a-2127-422b-91ae-364da2661108 github.com
access.redhat.com/errata/RHSA-2025:21448 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21139 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21138 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2025:21806 [email protected] access.redhat.com
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Arad Inbar for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2025-09-08T21:37:15.428ZReported to Red Hat.
CNA2025-11-12T00:00:00.000ZMade public.

Workarounds

CNA: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

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