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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 during bitmap decompression. The bug is a heap buffer overflow, so the main confirmed impact is denial of service, with possible code-execution risk depending on memory layout. The source bundle says 3.21.0 contains the fix.

Executive priority

Treat as high priority for endpoint and administrator workstations using FreeRDP. The strongest business risk is disruption from client crashes; memory corruption adds uncertainty and justifies timely patching even without confirmed exploitation.

Technical view

The issue is in freerdp_bitmap_decompress_planar: nSrcWidth and nSrcHeight were not validated against planar->maxWidth and maxHeight before planar RLE decoding. That can overflow a heap buffer in planar_decompress_plane_rle. The CVSS 4.0 score is 7.7 high, with network attack vector and no privileges required.

Likely exposure

Exposure is most likely on systems running FreeRDP clients or software embedding FreeRDP before 3.21.0, especially where users connect to unfamiliar, external, or compromised RDP servers. Downstream Linux packages may have separate vendor-fixed versions.

Exploitation context

The provided bundle does not show CISA KEV listing or confirmed active exploitation. The threat model is a malicious server triggering client-side memory corruption. Public details identify the vulnerable code path and fixed release, but the bundle does not provide weaponized exploit evidence.

Researcher notes

Focus validation on planar bitmap decompression and bounds checks before RLE decode. The advisory names CWE-122 and affected versions before 3.21.0. The source bundle supports DoS and potential heap corruption risk, but not reliable remote code execution or active exploitation.

Mitigation direction

  • Upgrade FreeRDP to 3.21.0 or a vendor-fixed downstream package.
  • Prioritize clients connecting to external, third-party, or unmanaged RDP servers.
  • Apply relevant Red Hat errata where FreeRDP is supplied by Red Hat.
  • Restrict FreeRDP use to trusted servers until patched.
  • Check vendor guidance for any distribution-specific backports or mitigations.

Validation and detection

  • Inventory FreeRDP client installations and embedded FreeRDP dependencies.
  • Confirm installed versions are 3.21.0 or vendor-fixed builds.
  • Review package advisories for Red Hat or other downstream distributions.
  • Identify users or services connecting to untrusted RDP servers.
  • Document remaining exceptions and compensating controls.
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-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-2026-23530 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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