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CVE Record

CVE-2026-45700: Heap-buffer-overflow write in planar bitmap decoder

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, FreeRDP's planar bitmap decoder has an out-of-bounds heap write when decoding RLE planar data. In libfreerdp/codec/planar.c, freerdp_bitmap_decompress_planar() validates the X destination coordinate nXDst against the caller-provided destination stride (nDstStep) even when it is writing into the internal temp buffer pTempData. An attacker can bypass the check with a large nDstStep and a large nXDst, causing planar_decompress_plane_rle() to write past the end of pTempData. This vulnerability is fixed in 3.26.0.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A malicious remote system can send specially formed bitmap data that corrupts memory in vulnerable FreeRDP versions. Successful exploitation could compromise confidentiality, integrity, and availability, but requires user interaction. FreeRDP fixed the flaw in version 3.26.0.

Executive priority

Treat this as a high-priority client-side update. Accelerate remediation where employees use FreeRDP against external, partner, or otherwise untrusted RDP services. The potential impact is severe, although confirmed exploitation is not established by the supplied evidence.

Technical view

Before 3.26.0, freerdp_bitmap_decompress_planar() compares the destination X coordinate against the caller-provided stride while writing to a separate temporary heap buffer. Crafted RLE planar data can combine large stride and X values to bypass validation, causing an out-of-bounds write in planar_decompress_plane_rle().

Likely exposure

Systems using FreeRDP versions earlier than 3.26.0 are potentially exposed when they decode attacker-controlled RLE planar bitmap data during an RDP interaction. The bundle does not establish which downstream packages or configurations enable the vulnerable path.

Exploitation context

CVSS 3.1 rates this 8.8: network reachable, low complexity, no privileges, and user interaction required, with potentially high impact. The supplied record is not in KEV, and the cited source bundle provides no evidence of active exploitation or a public exploit.

Researcher notes

The core defect is CWE-787 heap memory corruption caused by validating nXDst against nDstStep rather than the bounds of pTempData. Researchers should verify patched boundary handling and inspect downstream backports. Memory corruption may imply code execution, but the bundle does not demonstrate a working exploit or specific outcome.

Mitigation direction

  • Upgrade FreeRDP to version 3.26.0 or later.
  • For packaged distributions, install the applicable vendor-fixed package identified by official advisories.
  • Until updated, avoid using affected clients with untrusted or unexpected RDP services.
  • Prioritize systems whose users regularly initiate RDP sessions across less-trusted networks.

Validation and detection

  • Inventory FreeRDP libraries, clients, and embedded dependencies across endpoints and applications.
  • Confirm each installed or bundled FreeRDP version is 3.26.0 or later.
  • Check distribution advisories to verify whether vendor backports fix earlier package versions.
  • Review software composition results for statically linked or indirectly bundled FreeRDP copies.
Prepared
Confidence
high
Sources
6

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-787: 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-2026-45700 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
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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.

2CVSS vectors
5Timeline events
2ADP providers
16Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: noTechnical Impact: total

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
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9redhat-SADP
7.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——GitHub_M

Vulnerability scoring details

Base CVSS 4.0 score

7.7High
CVSS 4.0 vector shape for CVE-2026-45700Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

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: Out-of-bounds write in planar bitmap decoder allows arbitrary code execution
other:Red Hat severity ratingcvssV3_1
  • 2026-05-29T21:01:21.347Z: Reported to Red Hat.
  • 2026-05-29T19:44:12.385Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
FreeRDPFreeRDP< 3.26.0Listed
Weakness

CWE details

CWE-787

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

CWE-787 · source CWE mapping

Out-of-bounds Write

Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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