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FreeRDP Proxy EUVDEUVD-2026-115944

| CVE-2026-121412 HIGH
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-11-03 VulnCheck GHSA-63c5-cr4w-9mcg
7.1
CVSS 4.0 · Vendor: VulnCheck
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate and establish RDP session via proxy
  2. Delivery
    Reach a DVC selected for proxy interception
  3. Exploit
    Send DATA_FIRST declaring huge message length
  4. Execution
    Stream fragments without completing the message
  5. Impact
    Grow reassembly heap and exhaust proxy service

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource allocation limits
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

The attacker must be able to establish an RDP session through the FreeRDP proxy (hence authenticated, PR:L), and the deployment must have the proxy configured - via its configuration or a loaded module - to intercept a DVC that the attacker can reach. The tested path used a target-created AUDIO_INPUT channel together with FreeRDP's shipped dyn-channel-dump module. Exploitation is therefore limited to proxy deployments that actually enable DVC interception; plain client/server FreeRDP use without the interception proxy is not in scope. The impact is availability degradation only (traffic-proportional heap retention, approximately 6.55 MiB per incomplete message in the cited test, with ASan amplifying reported RSS).

Impact

This is a genuine but bounded denial-of-service issue, not a high-CVSS-but-low-real-risk artifact, though its priority is moderate rather than urgent. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N) and the VA:H/VC:N/VI:N profile correctly frame it as a network-reachable, low-complexity, authenticated availability-only flaw with no confidentiality or integrity impact - consistent with CWE-770/CWE-400 uncontrolled resource consumption. PR:L is well supported by the advisory prerequisite that the attacker must first establish an RDP session through the proxy, so this is not unauthenticated. The vuln.today decision label is 'this_week' (not act_now/emergency), aligning with a degrade-service-only impact rather than code execution. No CISA KEV listing and no EPSS score are present in the input, so widespread or active exploitation cannot be asserted; the GHSA documents a controlled lab reproduction (a 6,553,600-byte incomplete message), not in-the-wild use. Two signals should be flagged as conflicting: the CVE/package metadata states 'fixed in 3.32.2', yet the GHSA remediation text says 'No upstream fix was found in current master' - verify the actual fixed build with the vendor before relying on 3.32.2. Overall, prioritize patching of proxy deployments within the normal cycle, but treat it below RCE-class work.

Exploit ScenarioDerived

An attacker who can authenticate and establish an RDP session through a FreeRDP proxy configured to intercept a dynamic virtual channel declares a very large DATA_FIRST length and then streams fragments indefinitely without ever completing the message. The proxy appends every fragment to a reassembly buffer with no cumulative ceiling, so heap usage grows in proportion to the traffic sent, degrading or exhausting the shared proxy. No public working exploit code is identified in the input; the advisory describes only a lab reproduction.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available

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AnalysisAIv1 – Nov 03, 2026

Heap memory exhaustion in the FreeRDP proxy (versions 3.0.0 through 3.31.1) lets an authenticated client that already holds an RDP session through the proxy retain traffic-proportional heap by declaring a large DATA_FIRST length on an intercepted dynamic virtual channel and never completing the fragmented message. Only proxy deployments that actually enable DVC interception for an attacker-reachable channel are affected; the researcher's reproduction used a target-created AUDIO_INPUT channel with the shipped dyn-channel-dump module and measured roughly 6.55 MiB of retained data per incomplete message (ASan-inflated RSS figures were 324,012 KiB versus a 2,176 KiB control). Impact is availability only (CVSS 3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, CVSS 4.0 VA:H), no public exploit code was identified at time of analysis, and the issue is rated this_week rather than an emergency.

RemediationAI

Vendor-released patch: upgrade FreeRDP to 3.32.2, which the package data lists as the fixed version for the vulnerable range 3.0.0 through 3.31.1; verify the release contents against the GHSA advisory (https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-m7xq-5f7v-hjvw), since the advisory's remediation notes record that at the time of the research write-up no upstream fix was present in current master and recommended instead a trusted maximum declared message size, a checked cumulative limit before stream growth, partial-stream cleanup on rejection, and per-session/process resource accounting. Where upgrading is not immediately possible, reduce exposure by not selecting attacker-reachable DVCs for proxy interception (for example by unloading or not loading the dyn-channel-dump module and narrowing the proxy's interception configuration), accepting the loss of proxied channel inspection and dumping as the side effect, and by limiting proxy access to trusted accounts, since exploitation requires an established RDP session through the proxy (PR:L). Monitor proxy process memory for traffic-proportional growth as a detection signal for the incomplete-message pattern.

Affected VersionsENISA

FreeRDP 3.0.0 <3.32.2

Affected Packages

euvd freerdp fix: 3.32.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

FreeRDP's proxy mode sits between an RDP client and a target server and can intercept selected dynamic virtual channels (DVCs) so their traffic can be inspected or dumped. During DVC reassembly the proxy reads the peer-supplied 32-bit DATA_FIRST length and then appends each subsequent fragment to an in-memory reassembly stream, but it applies neither a trusted per-message ceiling on the declared length nor a checked cumulative limit before growing the stream (CWE-770 allocation of resources without limits, tracked upstream as CWE-400). Because a message is never required to be completed, the retained heap scales with the traffic the client sends and persists in the shared proxy process, so many incomplete messages degrade service for every session the proxy is carrying. The trigger path is documented by the reporter: the attacker must be able to open an RDP session through the proxy and the target must open a DVC that the proxy configuration or a loaded module has selected for interception; the tested configuration was a target-created AUDIO_INPUT channel with FreeRDP's bundled dyn-channel-dump module. Plain FreeRDP client or server use without the interception proxy is not in scope, and how the flaw would behave in other proxy module or channel configurations is not described in the available sources.

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Severity by source

Vendor (VulnCheck) PRIMARY 7.1 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
vuln.today AI 6.5 MEDIUM

Attacker needs an authenticated proxy session (PR:L) but no interaction or added complexity; impact is availability-only resource exhaustion with no confidentiality or integrity effect.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

2
Patch available
Nov 03, 2026 - 16:17 EUVD
CVE Published
Nov 03, 2026 - 14:28 cve.org
HIGH 7.1

DescriptionCVE.org

FreeRDP from 3.0.0 before 3.32.2 contains an uncontrolled resource consumption vulnerability in the proxy that lets connected clients retain heap memory via intercepted DVC message reassembly. Attackers can declare a large DATA_FIRST length and keep sending fragments without completing the message, growing proxy memory proportional to traffic and degrading service.

Technical POC Analysis

CWE-770 (Allocation of Resources Without Limits or Throttling) - the CVE record's mapping.

Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.

Executive ViewAI

Why It Matters

A heap memory exhaustion vulnerability in FreeRDP proxy versions 3.0.0-3.31.1 allows an authenticated user with an RDP session to retain large amounts of memory per incomplete message. While only deployments that enable dynamic virtual channel interception for attacker-reachable channels are affected, a successful attack could cause service unavailability. Leadership should care because this availability risk may disrupt remote access services for users relying on the proxy.

Business Impact: Medium
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include disabling DVC interception for attacker-reachable channels, monitoring and limiting per-session memory allocation, and restricting authenticated access to trusted users only.

Threat Intelligence Overview

Prevalence
Medium
FreeRDP is widely used, but the vulnerable proxy interception mode is a specific deployment
Social Media
1
Sightings
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS N/A
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Medium

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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Use-after-free in FreeRDP xf_clipboard_format_equal before 3.23.0. Clipboard format comparison uses freed memory. Fifth

CVE-2026-25953 CRITICAL POC
9.8 Feb 25

Use-after-free in FreeRDP xf_AppUpdateWindowFromSurface before 3.23.0. Surface-to-window update triggers memory corrupti

CVE-2026-25952 CRITICAL POC
9.8 Feb 25

Use-after-free in FreeRDP xf_SetWindowMinMaxInfo before version 3.23.0. X11 client window management triggers memory cor

CVE-2026-25959 CRITICAL POC
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Use-after-free in FreeRDP xf_cliprdr_provide_data clipboard handling before 3.23.0. Clipboard data exchange triggers mem

CVE-2026-22857 CRITICAL POC
9.8 Jan 14

FreeRDP IRP thread handler has a use-after-free where the IRP is freed by Complete() then accessed on the error path. Fi

CVE-2026-22854 CRITICAL POC
9.8 Jan 14

FreeRDP drive read heap overflow when server-controlled read length exceeds IRP output buffer. Fixed in 3.20.1. PoC avai

CVE-2026-22852 CRITICAL POC
9.8 Jan 14

FreeRDP client before 3.20.1 has a heap buffer overflow in AUDIN format processing. A malicious RDP server can corrupt m

CVE-2026-25955 CRITICAL POC
9.8 Feb 25

Use-after-free in FreeRDP xf_AppUpdateWindowFromSurface before 3.23.0. Different code path from CVE-2026-25953. PoC and

CVE-2024-32041 CRITICAL POC
9.8 Apr 22

FreeRDP is a free implementation of the Remote Desktop Protocol. Rated critical severity (CVSS 9.8), this vulnerability

CVE-2023-40574 CRITICAL POC
9.8 Aug 31

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CVE-2023-40569 CRITICAL POC
9.8 Aug 31

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CVE-2023-40567 CRITICAL POC
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