CVE-2026-55194Public exploitNetwork attack vector

Heap corruption via alloc_hint size mismatch

Published Aug 19, 2026 · Updated Aug 21, 2026

Heap-based buffer overflow in TS Gateway RPC handling in FreeRDP before 3.27.0 allows remote attackers to crash the client via crafted RESPONSE fragments. In libfreerdp/core/gateway/rpc_client.c, rpc_client_recv_fragment() grows the reassembly buffer from the server-declared alloc_hint instead of the actual StubLength and then copies the larger attacker-controlled stub with Stream_Write. Exposure requires a FreeRDP client to use TS Gateway or RD Gateway transport and receive a malicious PTYPE_RESPONSE; default builds can abort, while release builds risk heap corruption and possible code execution.

CVSS severity8.7
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in TS Gateway RPC handling in FreeRDP before 3.27.0 allows remote attackers to crash the client via crafted RESPONSE fragments. In libfreerdp/core/gateway/rpc_client.c, rpc_client_recv_fragment() grows the reassembly buffer from the server-declared alloc_hint instead of the actual StubLength and then copies the larger attacker-controlled stub with Stream_Write. Exposure requires a FreeRDP client to use TS Gateway or RD Gateway transport and receive a malicious PTYPE_RESPONSE; default builds can abort, while release builds risk heap corruption and possible code execution.

The record

CVE
CVE-2026-55194
Published
Aug 19, 2026
Updated
Aug 21, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-122, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 21, 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=< 3.27.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 3.27.0

Published CVSS scores

8.8Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.7GitHub_MCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
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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