Client memory over-read via unchecked NSC run length
Published Apr 22, 2024 · Updated Nov 3, 2025
Integer underflow in FreeRDP clients before 2.11.6 and 3.0.0 through 3.4.0 allows remote attackers to trigger an out-of-bounds read. The nsc_rle_decode function subtracts an attacker-controlled run length from its remaining-output counter without first verifying that the length fits, wrapping the counter and continuing decoder iterations. A malicious or compromised RDP server must negotiate the NSC codec; subsequent iterations read beyond the intended memory bounds, exposing process memory or crashing the client.
Summary
What happened
Integer underflow in FreeRDP clients before 2.11.6 and 3.0.0 through 3.4.0 allows remote attackers to trigger an out-of-bounds read. The nsc_rle_decode function subtracts an attacker-controlled run length from its remaining-output counter without first verifying that the length fits, wrapping the counter and continuing decoder iterations. A malicious or compromised RDP server must negotiate the NSC codec; subsequent iterations read beyond the intended memory bounds, exposing process memory or crashing the client.
The record
- CVE
- CVE-2024-32040
- Published
- Apr 22, 2024
- Updated
- Nov 3, 2025
- Vendor
- FreeRDP
- Product
- FreeRDP
- Classifications
- CWE-191
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 22, 2024CVE publishedPublication date reported by the CVE source.
- Nov 3, 2025Record 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.
- Affected versionversion=0 <2.11.6
- Affected versionversion=< 2.11.6
- Affected versionversion=>= 3.0.0, 3.5.0
- Affected versionversion=3.0.0 <=3.5.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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