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CVE Record

CVE-2026-23530: FreeRDP has heap-buffer-overflow in planar_decompress_plane_rle

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0,`freerdp_bitmap_decompress_planar` does not validate `nSrcWidth`/`nSrcHeight` against `planar->maxWidth`/`maxHeight` before RLE decode. 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 while processing compressed graphics data. The sources also note heap corruption risk, which could raise impact beyond denial of service depending on memory layout.

Executive priority

Treat as a high-priority client-side patching item where FreeRDP is used for remote administration. Urgency increases for teams connecting to third-party, lab, customer, or unmanaged RDP servers.

Technical view

The issue is a heap buffer overflow in planar RLE bitmap decompression. `freerdp_bitmap_decompress_planar` fails to validate source width and height against the planar context maximums before decode. A crafted server response can overrun heap memory in affected FreeRDP versions before 3.21.0.

Likely exposure

Exposure is primarily client-side: endpoints, jump boxes, automation, or applications using FreeRDP before 3.21.0, especially where users or tools connect to untrusted, attacker-controlled, or compromised RDP servers.

Exploitation context

The source bundle says KEV is false and provides no evidence of active exploitation. It describes malicious-server triggering and CVSS exploit maturity as proof-of-concept, but no safe public exploit details are included here.

Researcher notes

Focus validation on planar bitmap decompression bounds handling and package backports. The provided evidence supports crash and heap corruption risk, but does not prove reliable remote code execution or in-the-wild exploitation.

Mitigation direction

  • Upgrade FreeRDP to version 3.21.0 or later.
  • Apply relevant vendor packages, including Red Hat errata where applicable.
  • Avoid connecting vulnerable clients to untrusted or unknown RDP servers.
  • Check vendor guidance for distribution-specific fixed package versions.

Validation and detection

  • Inventory installed FreeRDP and libfreerdp package versions.
  • Confirm vulnerable systems are no longer running versions before 3.21.0.
  • Review RDP client use on workstations, jump hosts, and automation systems.
  • Verify Red Hat advisory applicability for managed Linux fleets.
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

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-122: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-23530 mapping review

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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: noTechnical 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-2026-23530Attack 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: Heap buffer overflow leading to denial of service and potential code execution from a malicious server.
other:Red Hat severity ratingcvssV3_1
  • 2026-01-19T18:00:59.270Z: Reported to Red Hat.
  • 2026-01-19T16:58:46.712Z: 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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