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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

FreeRDP before 3.26.0 can be made to write outside an internal heap buffer while decoding certain remote desktop bitmap data. This is a memory corruption flaw with high confidentiality, integrity, and availability impact, but the CVSS vector indicates user interaction is required.

Executive priority

Treat this as a high-priority patching item for workstations, jump hosts, and tools using FreeRDP. The business urgency is elevated because memory corruption can affect confidentiality, integrity, and availability, even though public active exploitation is not shown in the provided sources.

Technical view

The flaw is a CWE-787 heap out-of-bounds write in freerdp_bitmap_decompress_planar(). nXDst is checked against nDstStep while writes target pTempData, allowing oversized coordinates to reach planar_decompress_plane_rle() and write past the temporary buffer. FreeRDP fixed it in 3.26.0.

Likely exposure

Exposure is likely where FreeRDP clients, libraries, or applications embedding FreeRDP process RDP bitmap data using versions older than 3.26.0. Downstream Linux packages may be affected depending on vendor backports and errata status.

Exploitation context

The source bundle does not show CISA KEV listing or confirmed active exploitation. Network reachability and no privileges are required, but user interaction is listed, so realistic risk centers on users connecting with affected FreeRDP-based software to untrusted or compromised RDP endpoints.

Researcher notes

Key review points are the planar RLE decode path, coordinate validation against the wrong size boundary, and downstream package backports. Avoid assuming server-side exposure unless FreeRDP decoding is present in that role or product integration.

Mitigation direction

  • Upgrade FreeRDP to 3.26.0 or later.
  • Apply applicable vendor packages from Red Hat or other distributors.
  • Check vendor advisories before relying on version strings alone.
  • Limit FreeRDP use to trusted RDP servers until patched.
  • Identify applications that bundle libfreerdp independently.

Validation and detection

  • Inventory installed FreeRDP and libfreerdp package versions.
  • Confirm whether distributor packages include the CVE fix backport.
  • Review SBOMs for embedded FreeRDP dependencies older than 3.26.0.
  • Verify RDP client exposure to untrusted or external servers.
  • Track the listed Red Hat errata for environment-specific status.
Prepared
Confidence
high
Sources
9

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
8Source 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.

Open CWE intelligenceSame-CWE CVEs