Client crash via unchecked NSC input length
Published Aug 31, 2023 · Updated Nov 3, 2025
Out-of-bounds read in affected FreeRDP clients allows remote attackers to crash the client via malformed NSC image data. The general_LumaToYUV444 path processes its in buffer without verifying that sufficient bytes remain, so nsc_rle_decode reads past the allocation. Reachability requires an affected client to decode NSC graphics data from an attacker-controlled RDP server; FreeRDP Proxy is unaffected, and the demonstrated consequence is a client crash.
Summary
What happened
Out-of-bounds read in affected FreeRDP clients allows remote attackers to crash the client via malformed NSC image data. The general_LumaToYUV444 path processes its in buffer without verifying that sufficient bytes remain, so nsc_rle_decode reads past the allocation. Reachability requires an affected client to decode NSC graphics data from an attacker-controlled RDP server; FreeRDP Proxy is unaffected, and the demonstrated consequence is a client crash.
The record
- CVE
- CVE-2023-40188
- Published
- Aug 31, 2023
- Updated
- Nov 3, 2025
- Vendor
- FreeRDP
- Product
- FreeRDP
- Classifications
- CWE-125, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 31, 2023CVE 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=< 2.11.0
- Affected versionversion=>= 3.0.0-beta1, < 3.0.0-beta3
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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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