CVE-2026-55827

FreeRDP: Heap out-of-bounds write in RemoteFX (RFX) Cache Bitmap V3 decode

HIGH
8.8
CVSS Score
Published: July 10, 2026 at 07:47 PM UTC
Updated: July 15, 2026 at 05:17 AM UTC
1 product affected across 1 vendorFreeRDP

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Severity
HIGH8.8
Exploit prediction
EPSS 0.5%
SSVC
PoC

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.1, FreeRDP clients launched with the non-default /cache:codec:rfx option pass desktop stride and height to RemoteFX decoding for Cache Bitmap V3 data while allocating bitmap->data only for the smaller DstWidth and DstHeight in gdi_Bitmap_Decompress, allowing a malicious RDP server to trigger a heap out-of-bounds write with attacker-controlled offset and content. This issue is fixed in version 3.27.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.27.1
Affected range stops below 3.27.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMExploitMitigationVendor Advisory
Source: cverecord
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-c495-h83v-3prp
x_refsource_MISCPatch
Source: cverecord
https://github.com/FreeRDP/FreeRDP/pull/12899
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.1

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-131CWE-787

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