LiveActive security incident?Get immediate response
CVE Record

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.

MediumCVSS 5.9Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw can let an attacker overwhelm a kdcproxy server by forcing it to process an unbounded TCP response from a hostile KDC. The impact is service availability, not data theft. Business urgency is highest where kdcproxy supports Kerberos access for critical identity workflows.

Executive priority

Treat as a timely patching item for identity infrastructure, especially internet-facing or broadly reachable kdcproxy deployments. It is not presented as actively exploited, but denial of authentication proxy service can disrupt business operations.

Technical view

python-kdcproxy fails to bound TCP upstream response buffering and repeatedly copies incomplete response streams, causing excessive memory and CPU use. The attack depends on making kdcproxy connect to an attacker-controlled KDC, such as through SSRF. Concurrent requests can overflow accept queues and deny legitimate Kerberos proxy traffic.

Likely exposure

Exposure is most likely in Red Hat Enterprise Linux environments running affected python-kdcproxy or idm module builds. Systems not using kdcproxy, or unable to route proxy requests toward attacker-controlled KDC infrastructure, have lower practical exposure.

Exploitation context

The bundle does not show KEV listing or active exploitation. Exploitation is network-reachable but high complexity because the attacker must influence kdcproxy's upstream KDC connection. The expected outcome is denial of service through memory, CPU, or connection queue exhaustion.

Researcher notes

The key research condition is upstream control: the attacker must get kdcproxy to connect to a malicious KDC. Evidence supports CWE-770 resource exhaustion and availability-only CVSS impact. The source bundle does not provide safe public exploit status or detailed operational mitigations beyond vendor updates.

Mitigation direction

  • Apply the relevant Red Hat RHSA updates for affected RHEL streams.
  • Check upstream latchset kdcproxy guidance and fixes before relying on local workarounds.
  • Restrict who can reach kdcproxy endpoints where operationally possible.
  • Review SSRF or configuration paths that could steer kdcproxy to untrusted KDCs.
  • Monitor kdcproxy hosts for abnormal memory, CPU, and connection queue pressure.

Validation and detection

  • Inventory systems for python-kdcproxy packages or affected RHEL idm module streams.
  • Compare installed package versions against the Red Hat affected versions and errata.
  • Confirm whether kdcproxy is enabled and reachable on identified systems.
  • Review routing and application paths that can influence upstream KDC selection.
  • Check monitoring for recent unexplained kdcproxy resource spikes or service denials.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-770: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Cloud metadata behavior lookup

The CVE wording references SSRF or metadata access, so cloud discovery and credential material review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2025-59089 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.9 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
5Timeline events
2ADP providers
18Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.9CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H2.23.6redhat

Vulnerability scoring details

Base CVSS 3.1 score

5.9Medium
CVSS 3.1 vector shape for CVE-2025-59089Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineredhat

    Reported to Red Hat.

  2. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  3. Source timelineredhat

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
latchsetkdcproxykdcproxy, 0unaffected
Red HatRed Hat Enterprise Linux 10python-kdcproxy, 0:1.0.0-19.el10_1affected
Red HatRed Hat Enterprise Linux 10.0 Extended Update Supportpython-kdcproxy, 0:1.0.0-19.el10_0affected
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Supportpython-kdcproxy, 0:0.3.2-3.el7_9.3affected
Red HatRed Hat Enterprise Linux 8idm:client, 8100020251103113748.143e9e98affected
Red HatRed Hat Enterprise Linux 8idm:DL1, 8100020251028161822.823393f5affected
Red HatRed Hat Enterprise Linux 8.2 Advanced Update Supportidm:DL1, 8020020251106022345.792f4060affected
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportidm:DL1, 8040020251103205102.5b01ab7eaffected
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onidm:DL1, 8040020251103205102.5b01ab7eaffected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportidm:DL1, 8060020251030180424.ada582f1affected
Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update Serviceidm:DL1, 8060020251030180424.ada582f1affected
Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP Solutionsidm:DL1, 8060020251030180424.ada582f1affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Serviceidm:DL1, 8080020251029082621.b0a6ceeaaffected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionsidm:DL1, 8080020251029082621.b0a6ceeaaffected
Red HatRed Hat Enterprise Linux 9python-kdcproxy, 0:1.0.0-9.el9_7affected
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutionspython-kdcproxy, 0:1.0.0-7.el9_0.1affected
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutionspython-kdcproxy, 0:1.0.0-7.el9_2.1affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supportpython-kdcproxy, 0:1.0.0-7.el9_4.1affected
Red HatRed Hat Enterprise Linux 9.6 Extended Update Supportpython-kdcproxy, 0:1.0.0-9.el9_6affected
Weakness

CWE details

CWE-770

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-770 · source CWE mapping

Allocation of Resources Without Limits or Throttling

Allocation of Resources Without Limits or Throttling represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs