CVE-2026-22856Public exploitNetwork attack vector

Client crash via unsynchronized serial IRP lookup

Published Jan 14, 2026 · Updated Jan 14, 2026

Use-after-free in FreeRDP clients before 3.20.1 allows remote attackers controlling RDP servers to crash clients or corrupt heap memory. The serial-channel create_irp_thread path reads serial->IrpThreads without the lock used by the concurrent close path, which removes and frees the traversed list node. Exploitation requires a client to connect to a malicious or compromised RDP server with serial redirection active; confirmed impact is a client crash, while code execution depends on allocator behavior and heap layout.

CVSS severity8.1
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in FreeRDP clients before 3.20.1 allows remote attackers controlling RDP servers to crash clients or corrupt heap memory. The serial-channel create_irp_thread path reads serial->IrpThreads without the lock used by the concurrent close path, which removes and frees the traversed list node. Exploitation requires a client to connect to a malicious or compromised RDP server with serial redirection active; confirmed impact is a client crash, while code execution depends on allocator behavior and heap layout.

The record

CVE
CVE-2026-22856
Published
Jan 14, 2026
Updated
Jan 14, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-362, CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 14, 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=< 3.20.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 3.20.1

Published CVSS scores

6.8GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/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 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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-416Use After Free
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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