CVE-2026-55827Public exploitNetwork attack vector

Client code execution via RemoteFX stride mismatch

Published Jul 10, 2026 · Updated Jul 10, 2026

Heap out-of-bounds write in FreeRDP before 3.27.1 allows remote attackers to execute code in connecting clients via crafted RDP data. GDI's gdi_Bitmap_Decompress passes desktop stride and height to the RemoteFX decoder although bitmap->data is sized only for smaller Cache Bitmap V3 dimensions, so attacker-chosen tile positions drive pixel writes past the heap allocation. Exploitation requires a client launched with the non-default /cache:codec:rfx option to connect to a malicious or compromised RDP server, enabling controlled instruction-pointer corruption or a client crash.

CVSS severity7.5
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap out-of-bounds write in FreeRDP before 3.27.1 allows remote attackers to execute code in connecting clients via crafted RDP data. GDI's gdi_Bitmap_Decompress passes desktop stride and height to the RemoteFX decoder although bitmap->data is sized only for smaller Cache Bitmap V3 dimensions, so attacker-chosen tile positions drive pixel writes past the heap allocation. Exploitation requires a client launched with the non-default /cache:codec:rfx option to connect to a malicious or compromised RDP server, enabling controlled instruction-pointer corruption or a client crash.

The record

CVE
CVE-2026-55827
Published
Jul 10, 2026
Updated
Jul 10, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-787, CWE-131, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.27.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 3.27.1

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.5GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-131Incorrect Calculation of Buffer Size
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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