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CVE Record

CVE-2026-23532: FreeRDP has heap-buffer-overflow in gdi_SurfaceToSurface

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, a client-side heap buffer overflow occurs in the FreeRDP client’s `gdi_SurfaceToSurface` path due to a mismatch between destination rectangle clamping and the actual copy size. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.

HighCVSS 7.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

FreeRDP clients before 3.21.0 can be crashed by a malicious RDP server through a heap buffer overflow. The main confirmed impact is denial of service, with possible code-execution risk depending on memory layout. Organizations should prioritize client updates where FreeRDP is used to access remote desktops.

Executive priority

Treat as high priority for environments using FreeRDP, especially support, administration, and jump-host workflows. There is no confirmed active exploitation in the bundle, but the vulnerable component handles remote server-controlled data and has a released fix.

Technical view

The flaw is a CWE-122 heap buffer overflow in FreeRDP's gdi_SurfaceToSurface path. Source data says destination rectangle clamping can disagree with the actual copy size, allowing a malicious server to trigger client-side memory corruption. FreeRDP 3.21.0 contains the fix.

Likely exposure

Exposure is limited to systems running FreeRDP client versions earlier than 3.21.0, including downstream packages until vendor fixes are applied. Risk is higher where users or automation connect FreeRDP clients to untrusted or externally controlled RDP servers.

Exploitation context

The bundle does not show CISA KEV listing or confirmed active exploitation. The attack context is a malicious server interacting with a vulnerable FreeRDP client. The stated outcome is crash and potential heap corruption; reliable code execution is not established by the provided evidence.

Researcher notes

Focus analysis on the gdi_SurfaceToSurface copy path and bounds relationship between destination clamping and copy size. The sources support crash and potential heap corruption, but not weaponized exploitation. Distro package status should be checked against vendor advisories rather than upstream version alone.

Mitigation direction

  • Upgrade FreeRDP to version 3.21.0 or later.
  • Apply applicable vendor backported fixes, including relevant Red Hat advisories.
  • Restrict FreeRDP use to trusted RDP servers and gateways.
  • Review vendor guidance for unsupported or embedded FreeRDP builds.
  • Prioritize endpoints and jump hosts that initiate RDP sessions.

Validation and detection

  • Inventory FreeRDP client versions across workstations, servers, and containers.
  • Confirm no deployed FreeRDP package is older than 3.21.0 unless backported.
  • Check Red Hat advisory status for affected enterprise packages.
  • Review endpoint crash telemetry for FreeRDP client instability.
  • Validate RDP client workflows avoid unknown or untrusted servers.
Prepared
Confidence
high
Sources
10

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-122: 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.

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cve · low confidence lookup

CVE-2026-23532 mapping review

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

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.7 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

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.

2CVSS vectors
5Timeline events
2ADP providers
20Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

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
7.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P——GitHub_M
7.6CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H2.84.7redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

7.7High
CVSS 4.0 vector shape for CVE-2026-23532Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

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

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPfreerdp: FreeRDP: Denial of Service and potential code execution via client-side heap buffer overflow
other:Red Hat severity ratingcvssV3_1
  • 2026-01-19T18:02:13.669Z: Reported to Red Hat.
  • 2026-01-19T17:03:51.328Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
FreeRDPFreeRDP< 3.21.0Listed
Weakness

CWE details

CWE-122

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

CWE-122 · source CWE mapping

Heap-based Buffer Overflow

Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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